Hi. I had the same issue and this works for me.
serverless.yml
service:
name: pow
provider:
name: aws
runtime: nodejs8.10
resources:
${file(./main-config.yml)}
main-config.yml
- ${file(./part1.yml)}
- ${file(./part2.yml)}
....
part1.yml
Resources:
Test1:
Type: AWS::S3::Bucket
Properties:
BucketName: lkawjef-aa11
part2.yml
Resources:
Test2:
Type: AWS::S3::Bucket
Properties:
BucketName: lkawjef-aaz7zzz