بسم الله الرحمن الرحيم
If your wife permanently stays with you except seven or ten days in two months, while this is the schedule of the whole year and she visits her parents’ house only for seven or ten days as guest, then in such a case the parental house ceased to be a native place for your wife. If she stays there for less than fifteen days then she shall offer qasr salah.
Allah knows Best!
Darul Uloom Deoband
This answer was collected from the official ifta website of Darul Uloom Deoband in India.