diff --git a/controllers/provisioners/eks/cloud.go b/controllers/provisioners/eks/cloud.go
index 4eb10b1b..5181a5d3 100644
--- a/controllers/provisioners/eks/cloud.go
+++ b/controllers/provisioners/eks/cloud.go
@@ -408,6 +408,19 @@ func (d *DiscoveredState) SetClusterNodes(nodes *corev1.NodeList) {
 func (d *DiscoveredState) GetClusterNodes() *corev1.NodeList {
 	return d.ClusterNodes
 }
+func (d *DiscoveredState) GetRunningInstanceTypes() []string {
+	types := make([]string, 0)
+	if d.ScalingGroup == nil {
+		return types
+	}
+	for _, t := range d.ScalingGroup.Instances {
+		instanceType := aws.StringValue(t.InstanceType)
+		if !common.ContainsEqualFold(types, instanceType) {
+			types = append(types, instanceType)
+		}
+	}
+	return types
+}
 
 func (d *DiscoveredState) SetSubFamilyFlexiblePool(pool map[string][]InstanceSpec) {
 	d.InstancePool.SubFamilyFlexiblePool = InstancePool{
diff --git a/controllers/provisioners/eks/eks_test.go b/controllers/provisioners/eks/eks_test.go
index a50c1c60..2fd2f1d3 100644
--- a/controllers/provisioners/eks/eks_test.go
+++ b/controllers/provisioners/eks/eks_test.go
@@ -309,6 +309,17 @@ func MockTagDescription(key, value string) *autoscaling.TagDescription {
 	}
 }
 
+func MockTemplateOverrides(weight string, types ...string) []*autoscaling.LaunchTemplateOverrides {
+	overrides := make([]*autoscaling.LaunchTemplateOverrides, 0)
+	for _, t := range types {
+		overrides = append(overrides, &autoscaling.LaunchTemplateOverrides{
+			InstanceType:     aws.String(t),
+			WeightedCapacity: aws.String(weight),
+		})
+	}
+	return overrides
+}
+
 func MockScalingGroup(name string, withTemplate bool, t ...*autoscaling.TagDescription) *autoscaling.Group {
 	asg := &autoscaling.Group{
 		AutoScalingGroupName: aws.String(name),
@@ -316,6 +327,11 @@ func MockScalingGroup(name string, withTemplate bool, t ...*autoscaling.TagDescr
 		MinSize:              aws.Int64(3),
 		MaxSize:              aws.Int64(6),
 		VPCZoneIdentifier:    aws.String("subnet-1,subnet-2,subnet-3"),
+		Instances: []*autoscaling.Instance{
+			{
+				InstanceType: aws.String("m5.xlarge"),
+			},
+		},
 	}
 
 	if withTemplate {
diff --git a/controllers/provisioners/eks/helpers.go b/controllers/provisioners/eks/helpers.go
index 37ebb645..32bfbee8 100644
--- a/controllers/provisioners/eks/helpers.go
+++ b/controllers/provisioners/eks/helpers.go
@@ -1100,10 +1100,15 @@ func (ctx *EksInstanceGroupContext) GetOverrides() []*autoscaling.LaunchTemplate
 		primaryType   = configuration.InstanceType
 		mixedPolicy   = configuration.GetMixedInstancesPolicy()
 		state         = ctx.GetDiscoveredState()
+		runningTypes  = state.GetRunningInstanceTypes()
 	)
 	overrides := []*autoscaling.LaunchTemplateOverrides{}
+	if mixedPolicy == nil {
+		return overrides
+	}
 
-	if mixedPolicy != nil && mixedPolicy.InstanceTypes != nil {
+	// Create overrides from specific instanceTypes or derive from instancePool
+	if mixedPolicy.InstanceTypes != nil {
 		overrides = append(overrides, &autoscaling.LaunchTemplateOverrides{
 			InstanceType:     aws.String(primaryType),
 			WeightedCapacity: aws.String("1"),
@@ -1115,18 +1120,33 @@ func (ctx *EksInstanceGroupContext) GetOverrides() []*autoscaling.LaunchTemplate
 				WeightedCapacity: aws.String(weightStr),
 			})
 		}
-		return overrides
+	} else if mixedPolicy.InstancePool != nil {
+		if strings.EqualFold(*mixedPolicy.InstancePool, string(SubFamilyFlexible)) {
+			if pool, ok := state.InstancePool.SubFamilyFlexiblePool.GetPool(primaryType); ok {
+				for _, p := range pool {
+					overrides = append(overrides, &autoscaling.LaunchTemplateOverrides{
+						InstanceType:     aws.String(p.Type),
+						WeightedCapacity: aws.String(p.Weight),
+					})
+				}
+			}
+		}
 	}
 
-	switch {
-	case strings.EqualFold(*mixedPolicy.InstancePool, string(SubFamilyFlexible)):
-		if pool, ok := state.InstancePool.SubFamilyFlexiblePool.GetPool(primaryType); ok {
-			for _, p := range pool {
-				overrides = append(overrides, &autoscaling.LaunchTemplateOverrides{
-					InstanceType:     aws.String(p.Type),
-					WeightedCapacity: aws.String(p.Weight),
-				})
-			}
+	// if some type is already running in the group (when switching from LaunchConfiguration to LaunchTemplate), it must be included in overrides
+	// Once the type is replaced with the new primary type it will no longer be added as an override
+	var overrideTypes = make([]string, 0)
+	for _, o := range overrides {
+		override := aws.StringValue(o.InstanceType)
+		overrideTypes = append(overrideTypes, override)
+	}
+
+	for _, t := range runningTypes {
+		if !common.ContainsEqualFold(overrideTypes, t) {
+			overrides = append(overrides, &autoscaling.LaunchTemplateOverrides{
+				InstanceType:     aws.String(t),
+				WeightedCapacity: aws.String("1"),
+			})
 		}
 	}
 
diff --git a/controllers/provisioners/eks/helpers_test.go b/controllers/provisioners/eks/helpers_test.go
index 2fdcc6e6..76dd236e 100644
--- a/controllers/provisioners/eks/helpers_test.go
+++ b/controllers/provisioners/eks/helpers_test.go
@@ -806,6 +806,85 @@ func TestGetMountOpts(t *testing.T) {
 	}
 }
 
+func TestGetOverrides(t *testing.T) {
+	var (
+		g             = gomega.NewGomegaWithT(t)
+		k             = MockKubernetesClientSet()
+		ig            = MockInstanceGroup()
+		configuration = ig.GetEKSConfiguration()
+		asgMock       = NewAutoScalingMocker()
+		iamMock       = NewIamMocker()
+		eksMock       = NewEksMocker()
+		ec2Mock       = NewEc2Mocker()
+		ssmMock       = NewSsmMocker()
+	)
+
+	w := MockAwsWorker(asgMock, iamMock, eksMock, ec2Mock, ssmMock)
+	ctx := MockContext(ig, k, w)
+	state := ctx.GetDiscoveredState()
+
+	instancePool := "SubFamilyFlexible"
+
+	tests := []struct {
+		primaryType        string
+		scalingGroup       *autoscaling.Group
+		mixedInstancesSpec *v1alpha1.MixedInstancesPolicySpec
+		expectedOverrides  []*autoscaling.LaunchTemplateOverrides
+	}{
+		{
+			primaryType:  "m5.xlarge",
+			scalingGroup: MockScalingGroup("asg-1", true),
+			mixedInstancesSpec: &v1alpha1.MixedInstancesPolicySpec{
+				InstanceTypes: []*v1alpha1.InstanceTypeSpec{
+					{
+						Type:   "m5a.xlarge",
+						Weight: 1,
+					},
+					{
+						Type:   "m5g.xlarge",
+						Weight: 1,
+					},
+				},
+			},
+			expectedOverrides: MockTemplateOverrides("1", "m5a.xlarge", "m5g.xlarge", "m5.xlarge"),
+		},
+		{
+			primaryType:  "m5.xlarge",
+			scalingGroup: MockScalingGroup("asg-1", true),
+			mixedInstancesSpec: &v1alpha1.MixedInstancesPolicySpec{
+				InstancePool: &instancePool,
+			},
+			expectedOverrides: MockTemplateOverrides("1", "m5.xlarge"),
+		},
+		{
+			primaryType:  "t2.xlarge",
+			scalingGroup: MockScalingGroup("asg-1", true),
+			mixedInstancesSpec: &v1alpha1.MixedInstancesPolicySpec{
+				InstanceTypes: []*v1alpha1.InstanceTypeSpec{
+					{
+						Type:   "t2a.xlarge",
+						Weight: 1,
+					},
+					{
+						Type:   "t2g.xlarge",
+						Weight: 1,
+					},
+				},
+			},
+			expectedOverrides: MockTemplateOverrides("1", "t2a.xlarge", "t2g.xlarge", "t2.xlarge", "m5.xlarge"),
+		},
+	}
+
+	for i, tc := range tests {
+		t.Logf("Test #%v - %+v", i, tc.expectedOverrides)
+		configuration.MixedInstancesPolicy = tc.mixedInstancesSpec
+		state.ScalingGroup = tc.scalingGroup
+		ig.Spec.EKSSpec.EKSConfiguration.InstanceType = tc.primaryType
+		overrides := ctx.GetOverrides()
+		g.Expect(overrides).To(gomega.ConsistOf(tc.expectedOverrides))
+	}
+}
+
 func TestGetUserDataStages(t *testing.T) {
 	var (
 		g             = gomega.NewGomegaWithT(t)