Pull Request Title(not the default one but edited) to be in pull request commit message

In Bitbucket Server 4.5.1, the pull request picks up the latest commit message of FromREF(pull request source branch) as Pull request Title and is been included as part of pull request merge commit message. But if I edit the pull request title while creating the pull request or after creating the pull request, the pull request merge commit message still only includes the default title picked up by bitbucket server initially(i.e, latest commit message of FromREF ) but not the newly changed title.

Is there a workaround for this solution? Via API?