When merging topic branch "B" in "A" using git merge, I get some conflicts. I >know all the conflicts can be solved using the version in "B".
I am aware of git merge -s ours. But what I want is something like git merge >-s their.
I'm assuming that you created a branch off of master and now want to merge back into master, overriding any of the old stuff in master. That's exactly what I wanted to do when I came across this post.
Do exactly what it is you want to do, Except merge the one branch into the other first. I just did this, and it worked great.
git checkout Branch
git merge master -s ours
Then, checkout master and merge your branch in it (it will go smoothly now):
git checkout master
git merge Branch