My mother found milchig Tupperware covers and containers in the fleishig cabinet and she doesn’t know if the cleaning lady washed them in the milchig sink or just by mistake put them away there and really washed them in the milchig sink.
Can she still use them for milchigs?
You can still use them for milchigs. This is because there are number of lenient factors here. Maybe it wasn’t washed with the fleishigs at all, to per because it is only a safek, and secondly because the and even if it was washed together, maybe the fleishig dishes were not a ben yomo, or the water wasn’t considered a kli rishon.
Rema Y:D 95-3