Use getattr to access m2m and related data
Revert "Use getattr to access m2m and related data"

This reverts commit 74dec7e2f59f7e0b056a24f2f73926de2f5b180f.
Revert "Use a single serializer for list data"

This reverts commit ae1fcb465255fb8df94ace011196c52c58321b89.
Instantiate a new sibling serializer instead of copying current