That is precisely the problem you can't pull your AB Test into your XT test. Instead of having some changes in AB test and some in XT test have all changes in a different XT experience.
I'll try to give you an example
1. In my AB test for ExpB on URL: www.domain.com/cats I change picture of the cat from a white cat to black cat.
2. In my XT test for the first Experience on URL: www.domain.com I change greeting from hello cat lovers to "hello animal lovers"
I then think about it some more and decide that it would be really cool to have both changes show for a subset of visitors that I identify as "visitors who own 2 cats and 1 dog"
In order to accomplish this I set up a new XT activity and give the first experience an audience of "visitors who own 2 cats and 1 dog" and then for that experience I first browse to www.domain.com and change the greeting to: "hello animal lovers" and then browse to www.domain.com/cats and change the picture of the cat from a white cat to a black cat. So now I have one experience that applies both changes. Hope this helped illustrate a little better.