The Timeline refers to our galaxy as the Combine: http://rules.swcombine.com/?Timeline

Does that mean that "Combine" is the IC name of the galaxy? If not, does the galaxy have an IC name?

I ask because I'm wondering if it would be o.k. to include "Combine" in the name of a new faction or non-faction group.

It's called simply The Galaxy. Combine is an OOC term that should not be used ICly.