Serverless framework AppSync service with custom split stacks

serverless.yml

custom:
  splitStacks:
    nestedStackCount: 50
    perFunction: false
    perType: false
    perGroupFunction: false

stacks-map.js

module.exports = (resource, logicalId) => {
    console.log(resource.Type, logicalId);
  
    // Keep the deployment bucket with default setup
    if( logicalId.startsWith('ServerlessDeploymentBucket') || resource.Type == 'AWS::Lambda::Permission'){
        return 
    }

    if( (resource.Type == 'AWS::S3::Bucket' || resource.Type == 'AWS::S3::BucketPolicy') ){
        return { destination: 'S3GroupStack', allowSuffix: true, force: true };
    }
  
    if ( resource.Type == "AWS::Logs::LogGroup" && !logicalId.endsWith('GraphQlApiLogGroup') ) {
        return { destination: 'LogGroupsStack', allowSuffix: true, force: true };
    }
  
    // Appsync specific resources
    if( resource.Type == 'AWS::AppSync::GraphQLSchema' ||
        resource.Type == 'AWS::AppSync::FunctionConfiguration' || 
        resource.Type == 'AWS::AppSync::DataSource' || 
        resource.Type == 'AWS::AppSync::Resolver' ){
        return { destination: 'AppSync', allowSuffix: true, force: true };
    }    

    // Falls back to default
};

Likely errors:

• Circular dependencies - This you can easily understand and resolve by going through your resources and keeping the related resources in the same stack.
• Resource already exists in another stack - This will come if you are trying to deploy the changes on the existing stage that is not using split stack or has a different stack structure. For me, the closest solution was to deploy a new stage.