VPC config in serverless.yml

Serverless Framework
1

VPC config in serverless.
provider:
vpc:
securityGroupIds:
- sg-xxxxxxx
subnetIds:
- subnet-xxxxxxx
- subnet-xxxxxxx

How can we import the value like SAM based on VPC name like

VpcConfig:
         SecurityGroupIds:
           - !Sub '${DefaultSecurityGroupId}'
         SubnetIds:
           - 'Fn::ImportValue': !Sub '${ParentVPCName}-SubnetBPrivate'
           - 'Fn::ImportValue': !Sub '${ParentVPCName}-SubnetCPrivate'

Please suggest.

Thanks,
Dilip