My thought would be to cut her loose but be kind, the age difference carries along a lot of baggage even if she were ideal. A band that's already got a path doesn't need to reroute itself for a sometime, somewhat, maybe, she needs to completely ajust to find her place with you all not all of you readjusting to suit her fitting in, if she doesn't like what your doing why's she there, she's getting something & if it is the attention then like Mick says she's more important than the music & the band. Good luck. Barry