What could be happening is that because your daughter previously threw a backup ball that in attempting to throw a hook or curve ball she is close to throwing a full roller. A full roller is achieved by having your fingers in the 5 o'clock to 4 o'clock position but instead of turning counterclockwise at the release point she is probably turning the ball clockwise at the release point, say from 4:30 to 5:00 as her instinct is to throw a backup even though her fingers are in a position to throw a hook.
A full roller's track is between the thumbhole and the fingerholes. If you don't come out of it conducive to a full roller, expect to throw a 'thumper". Walter Ray sometimes throws a thumper at spares - probably the result of his hand turning a bit clockwise in an attempt to go straight.
My son when he was eleven threw a backup ball. Despite my efforts I could not break him of the habit. Finally I bought him a Lady Cobra which solved his backup problem. Unfortunately when he entered high school he gave up bowling. The fact that your daughter's ball track is so erratic tells me that either she is not paying attention as to where her fingers are initially in her stance or her delivery changes from shot to shot. A small investment in an inexpensive wrist support like the Weber
Wristmaster might help solve her problem.