I don't think she will be. The shows are supposed to be 3 hours long so I just don't see there being time for Vanessa to open. But then again, when Stevie toured with Don Henley in '05, they had an opener. So I guess there is always the possibility.
Stevie has a new album coming out May 3 and she plans on touring for that as well. I imagine that's when Vanessa will tour with her again, if she's going to. (Fingers crossed).