Enquiring about food given by people who are involved in bid'aat

I reside in Kashmir. Here our neighbours usually send raw meat or rice preparations to each other. Some people among them are those who go to dargahs etc. Is it necessary to enquire from them about in whose name they have prepared these rice preparations or sacrificed the animals before eating it or accepting it. Also it may not be possible every time to ask them in whose name they have sacrificed the animal etc.