diff --git a/doc/getting_started/training.md b/doc/getting_started/training.md
index 4bbdf42e..c9d7b4e6 100644
--- a/doc/getting_started/training.md
+++ b/doc/getting_started/training.md
@@ -267,6 +267,16 @@ pytorch_job.create()
 ````
 `````
 
+For SDK jobs with several `ReplicaSpec` entries, quota allocation validates and
+resolves the main container's resources in every replica set using that replica's
+instance type. For example, a chief on `ml.g5.xlarge` and workers on
+`ml.p4d.24xlarge` receive their own GPU, CPU, memory, and EFA allocations. Replica
+sets without an instance type keep their explicit resources, including omitted
+resource mappings. Managed replicas can omit mappings to use instance defaults.
+If any replica set
+fails validation, allocation raises `ValueError` without partially updating the
+input job.
+
 ### Key Parameters
 
 When creating a training job, you'll need to specify:
diff --git a/src/sagemaker/hyperpod/training/hyperpod_pytorch_job.py b/src/sagemaker/hyperpod/training/hyperpod_pytorch_job.py
index f39bc07e..dd5e74ce 100644
--- a/src/sagemaker/hyperpod/training/hyperpod_pytorch_job.py
+++ b/src/sagemaker/hyperpod/training/hyperpod_pytorch_job.py
@@ -7,7 +7,7 @@
     EFA_RESOURCE_LIMIT_KEY,
 )
 from sagemaker.hyperpod.training.config.hyperpod_pytorch_job_unified_config import (
-    _HyperPodPytorchJob, HyperPodPytorchJobStatus
+    _HyperPodPytorchJob, HyperPodPytorchJobStatus, Resources
 )
 from sagemaker.hyperpod.common.config.metadata import Metadata
 from kubernetes import client, config, stream
@@ -100,20 +100,20 @@ def _process_replica_resources(cls, data):
             node_count = data.get('replicas', None)
 
             # Extract nested configuration with validation
-            template = data.get('template', {})
-            spec = template.get('spec', {})
+            template = data.get('template') or {}
+            spec = template.get('spec') or {}
             node_selector = spec.get('nodeSelector', {})
             instance_type = node_selector.get(INSTANCE_TYPE_LABEL) if node_selector else None
 
-            containers = spec.get('containers', [])
+            containers = spec.get('containers') or []
 
             if not containers:
                 raise ValueError("No containers found in template spec")
 
             container = containers[0]
-            resources = container.get('resources', {})
-            requests = resources.get('requests', {})
-            limits = resources.get('limits', {})
+            resources = container.get('resources') or {}
+            requests = resources.get('requests') or {}
+            limits = resources.get('limits') or {}
 
             # Check if accelerators are specified without instance_type
             accel_keys = ['accelerators', NVIDIA_RESOURCE_KEY, NEURON_RESOURCE_KEY]
@@ -200,8 +200,9 @@ def _process_replica_resources(cls, data):
             _resolve_default_cpu_values(instance_type, requests_values)
 
             # Update data with calculated values
-            data['template']['spec']['containers'][0]['resources']['requests'] = requests_values
-            data['template']['spec']['containers'][0]['resources']['limits'] = limits_values
+            resources['requests'] = requests_values
+            resources['limits'] = limits_values
+            container['resources'] = resources
 
             return data
         except KeyError as e:
@@ -215,22 +216,29 @@ def _get_container_resources(cls, replica_spec):
 
     @classmethod
     def allocate_quotas_if_applicable(cls, spec):
-        try:
-            spec_dict = spec.model_dump()
-            replica_spec = spec_dict['replicaSpecs'][0]
-            cls._process_replica_resources(replica_spec)
+        """Resolve every replica set's resources before updating the job.
 
-            # Update the original spec object directly
+        Replica sets without an instance type keep their explicit resources.
+        A validation failure in any replica set leaves the input job unchanged.
+        """
+        spec_dict = spec.model_dump()
+        allocations = []
+        for index, replica_spec in enumerate(spec_dict['replicaSpecs'] or []):
+            if cls._process_replica_resources(replica_spec) is None:
+                continue
             requests, limits = cls._get_container_resources(replica_spec)
-            spec.replicaSpecs[0].template.spec.containers[0].resources.requests = requests
-            spec.replicaSpecs[0].template.spec.containers[0].resources.limits = limits
+            allocations.append((index, requests, limits))
 
-            return spec
-        except ValueError as e:
-            raise ValueError(e)
-        except Exception as e:
-            # In case of any other exception, return original spec
-            return spec
+        # Validate all replica sets before mutating the caller's job.
+        for index, requests, limits in allocations:
+            container = spec.replicaSpecs[index].template.spec.containers[0]
+            if container.resources is None:
+                container.resources = Resources(requests=requests, limits=limits)
+            else:
+                container.resources.requests = requests
+                container.resources.limits = limits
+
+        return spec
 
     @_hyperpod_telemetry_emitter(Feature.HYPERPOD, "create_pytorchjob")
     def create(self, debug=False):
diff --git a/test/unit_tests/training/test_multi_replica_resource_allocation.py b/test/unit_tests/training/test_multi_replica_resource_allocation.py
new file mode 100644
index 00000000..042bacc2
--- /dev/null
+++ b/test/unit_tests/training/test_multi_replica_resource_allocation.py
@@ -0,0 +1,182 @@
+"""Every training replica set receives validation and quota allocation."""
+
+from copy import deepcopy
+from unittest.mock import patch
+
+from hyperpod_pytorch_job_template.v1_1.model import PyTorchJobConfig
+import pytest
+
+from sagemaker.hyperpod.training import HyperPodPytorchJob, Resources
+
+
+def make_multi_replica_job():
+    chief = PyTorchJobConfig(
+        job_name="multi-replica",
+        image="pytorch:latest",
+        instance_type="ml.g5.xlarge",
+        accelerators=1,
+    ).to_domain()
+    worker = PyTorchJobConfig(
+        job_name="worker",
+        image="pytorch:latest",
+        instance_type="ml.p4d.24xlarge",
+        accelerators=4,
+        replica_count=2,
+    ).to_domain()
+    chief.replicaSpecs[0].name = "chief"
+    worker.replicaSpecs[0].name = "workers"
+    chief.replicaSpecs.extend(worker.replicaSpecs)
+    return chief
+
+
+def test_all_replica_sets_receive_instance_specific_resources():
+    job = make_multi_replica_job()
+    resolved = HyperPodPytorchJob.allocate_quotas_if_applicable(job)
+    chief, workers = resolved.replicaSpecs
+    chief_resources = chief.template.spec.containers[0].resources
+    worker_resources = workers.template.spec.containers[0].resources
+
+    assert int(chief_resources.requests["nvidia.com/gpu"]) == 1
+    assert "vpc.amazonaws.com/efa" not in chief_resources.requests
+    assert int(worker_resources.requests["nvidia.com/gpu"]) == 4
+    assert int(worker_resources.limits["nvidia.com/gpu"]) == 4
+    assert int(worker_resources.requests["vpc.amazonaws.com/efa"]) == 4
+    assert int(worker_resources.limits["vpc.amazonaws.com/efa"]) == 4
+    assert "accelerators" not in worker_resources.requests
+    assert [replica.name for replica in resolved.replicaSpecs] == ["chief", "workers"]
+    assert workers.replicas == 2
+
+
+@pytest.mark.parametrize("unmanaged_index", [0, 1])
+def test_replica_without_instance_type_does_not_skip_other_replicas(unmanaged_index):
+    job = make_multi_replica_job()
+    unmanaged = job.replicaSpecs[unmanaged_index]
+    unmanaged.template.spec.nodeSelector = None
+    unmanaged.template.spec.containers[0].resources.requests = {"cpu": "1"}
+    unmanaged.template.spec.containers[0].resources.limits = {"cpu": "2"}
+    original = deepcopy(unmanaged.model_dump())
+
+    resolved = HyperPodPytorchJob.allocate_quotas_if_applicable(job)
+    assert resolved.replicaSpecs[unmanaged_index].model_dump() == original
+    managed = resolved.replicaSpecs[1 - unmanaged_index]
+    resources = managed.template.spec.containers[0].resources
+    assert "nvidia.com/gpu" in resources.requests
+    assert "accelerators" not in resources.requests
+
+
+@pytest.mark.parametrize("invalid", ["accelerator-capacity", "missing-instance-type"])
+def test_later_invalid_replica_is_rejected_without_partial_mutation(invalid):
+    job = make_multi_replica_job()
+    worker = job.replicaSpecs[1]
+    if invalid == "accelerator-capacity":
+        resources = worker.template.spec.containers[0].resources
+        resources.requests["accelerators"] = "9"
+        resources.limits["accelerators"] = "9"
+        expected_error = "exceeds instance capacity"
+    else:
+        worker.template.spec.nodeSelector = None
+        expected_error = "instance_type is required"
+    original = deepcopy(job.model_dump())
+
+    with pytest.raises(ValueError, match=expected_error):
+        HyperPodPytorchJob.allocate_quotas_if_applicable(job)
+    assert job.model_dump() == original
+
+
+@pytest.mark.parametrize("index", [0, 1])
+@pytest.mark.parametrize(
+    "resources",
+    [
+        None,
+        Resources(),
+        Resources(requests={"cpu": "1"}),
+        Resources(limits={"memory": "8Gi"}),
+    ],
+)
+def test_unmanaged_replica_with_optional_resources_preserves_other_allocations(
+    index, resources
+):
+    job = make_multi_replica_job()
+    unmanaged = job.replicaSpecs[index]
+    unmanaged.template.spec.nodeSelector = None
+    unmanaged.template.spec.containers[0].resources = resources
+    original = deepcopy(unmanaged.model_dump())
+    resolved = HyperPodPytorchJob.allocate_quotas_if_applicable(job)
+    assert resolved.replicaSpecs[index].model_dump() == original
+    managed_resources = (
+        resolved.replicaSpecs[1 - index].template.spec.containers[0].resources
+    )
+    assert "nvidia.com/gpu" in managed_resources.requests
+    assert "accelerators" not in managed_resources.requests
+
+
+@pytest.mark.parametrize(
+    "resources",
+    [
+        None,
+        Resources(),
+        Resources(requests={"cpu": "1"}),
+        Resources(limits={"memory": "8Gi"}),
+    ],
+)
+def test_managed_replica_with_optional_resources_is_allocated(resources):
+    job = make_multi_replica_job()
+    job.replicaSpecs[1].template.spec.containers[0].resources = resources
+    resolved = HyperPodPytorchJob.allocate_quotas_if_applicable(job)
+    chief_resources = resolved.replicaSpecs[0].template.spec.containers[0].resources
+    worker_resources = resolved.replicaSpecs[1].template.spec.containers[0].resources
+    assert int(chief_resources.requests["nvidia.com/gpu"]) == 1
+    assert "cpu" in worker_resources.requests
+    assert "memory" in worker_resources.requests
+    assert "accelerators" not in worker_resources.requests
+
+
+@patch("sagemaker.hyperpod.common.telemetry.telemetry_logging._send_telemetry_request")
+@patch("sagemaker.hyperpod.training.hyperpod_pytorch_job.client.CustomObjectsApi")
+@patch.object(HyperPodPytorchJob, "verify_kube_config")
+def test_create_serializes_allocations_with_optional_worker_resources(
+    verify_config, api, telemetry
+):
+    job = make_multi_replica_job()
+    job.metadata.namespace = "default"
+    worker = job.replicaSpecs[1]
+    worker.template.spec.nodeSelector = None
+    worker.template.spec.containers[0].resources = None
+    job.create()
+    body = api.return_value.create_namespaced_custom_object.call_args.kwargs["body"]
+    chief, worker_payload = body["spec"]["replicaSpecs"]
+    requests = chief["template"]["spec"]["containers"][0]["resources"]["requests"]
+    assert int(requests["nvidia.com/gpu"]) == 1
+    assert "cpu" in requests and "memory" in requests
+    assert "resources" not in worker_payload["template"]["spec"]["containers"][0]
+
+
+@patch("sagemaker.hyperpod.common.telemetry.telemetry_logging._send_telemetry_request")
+@patch("sagemaker.hyperpod.training.hyperpod_pytorch_job.client.CustomObjectsApi")
+@patch.object(HyperPodPytorchJob, "verify_kube_config")
+def test_create_rejects_invalid_later_replica_before_api_submission(
+    verify_config, api, telemetry
+):
+    job = make_multi_replica_job()
+    job.metadata.namespace = "default"
+    job.replicaSpecs[1].template.spec.nodeSelector = None
+    with pytest.raises(ValueError, match="instance_type is required"):
+        job.create()
+    api.assert_not_called()
+
+
+@pytest.mark.parametrize("replicas", [None, []])
+def test_missing_replica_list_remains_unchanged(replicas):
+    job = make_multi_replica_job()
+    job.replicaSpecs = replicas
+    assert HyperPodPytorchJob.allocate_quotas_if_applicable(job) is job
+    assert job.replicaSpecs == replicas
+
+
+def test_later_replica_without_template_fails_without_partial_mutation():
+    job = make_multi_replica_job()
+    job.replicaSpecs[1].template = None
+    original = deepcopy(job.model_dump())
+    with pytest.raises(ValueError, match="No containers found"):
+        HyperPodPytorchJob.allocate_quotas_if_applicable(job)
+    assert job.model_dump() == original