Include and reference CFN template as part of the upload

In the resources part of the serverless.yml I have something like this:

      Type: AWS::CloudFormation::Stack
        TemplateURL: ''

This successfully executes the referenced CFN template as a nested stack.
However for this to work, I need to upload the said CFN template ( cloudformation-script.cform ) to s3 first, then in serverless.yml point to the uploaded file , and only then do sls deploy .
Is there a way to somehow include the script in my serverless project, so that it would be uploaded along the other serverless resources, and reference it from sls script somehow? (maybe by relative URL)