If you can, I wouldn't give up yet BUT I would tell the family you are extending hte probation periods by 2 more weeks. You feel she will settle in within that time but should she not you will give notice.

If it looks like she may not full settle in another 2 weeks and you feel you won't survive longer than that then make sure it is clear that the probation period is still in play.

2.5yrs is much harder than 12months...at 12months you can easily distract and they forget. At 2.5 they are harder to keep distracted and are more emotional!