At the point where the new branch is built, it becomes equal to what you selected the branch from.
The difficult point of TFS merging (unlike, for example, for P4 integration or ClearCase merging) is that at any merge point A → B and B → A do not generate an equal number of merge candidates.
Let say that the branch A generates the branch B:
\
\
Let's say you make changes to A:
\
\
If you try to merge A '-> B, you will receive as a merge of candidates all your changes / source files that have been changed from A → A'.
But if you try to merge B → A ', you will not get any merge candidates at all.
This behavior is independent of the fact that A is "parent".
"A" B → A, :
(, , , , - TFS-: R.Banks)