A nice trick for dealing with stacked diffs in Phabricator is to use "git rebase -i" to modify diffs in the middle of the stack.  You can also insert "x arc diff" between lines to automatically update later diffs on Phabricator after a rebase lower down the stack.

You only need a single branch for the whole stack, and continually rebase it.  I also push the whole branch to github to get Travis to build it, but that's optional.