XF 1.2 Merging 4 xenforo licences into 1 XF based forum, how to do so ?

So i have 4 forums, xf everywhere, want to join them into one.
As i heard, xf doesn't have such function, i can import another forums, but not xf.

So anyway, i need some advise guys, where to i need to import 4 xf mysql databases, and then, move it into xf again.

First off i'm tried to do so with vanilla forum software, that has xf import tool, but, it's only for one database, so i can't import another mysql db's into it, because that's will overwrite any data before import process.

Does vbulletin can import multiple xf db's ? or mayb another forum software, mayb not forum software, some php script ?