After a merge squash or cherry pick. HOWTO sync branches

I have Topic B which is like a scratch pad with lots of small changes, reversions, corrections, but the end result is what I want.

If I merge squash or cherry pick Topic B into Master, is there a way to have the HEAD of Topic B be aligned with Master so that future work will be easy to maintain. Work may still go on in Topic B and I want to retain the history of development in it. But not all of it in Master.

Or, do I need to just keep track of the last commit that was merged into Master.

Thanks.

Putting request on hold. I did not realize/forgot merge will roll up all changes from the first commit selected and add to destination branch. DOH