We have a large team working on several releases at once. We use Bitbucket to create branches, pull requests for merging and auto-merge to merge forward to future release branches. We need a way to ensure that branches created from a release branch can only be merged to that release branch in a pull request.
One thought is to have a hook on branch creation that adds the 'parent' branch name to the new branch's description. Then another hook on pull request creation that verifies the destination branch matches the parent branch, or perhaps modifies the destination list to only include the parent release branch. This would also have to exempt release to release and release to develop merges triggered by the auto-merge