If you go to JewishGen.org, go to the Communities database and
do a search, Domoncheo does not come up at all.
You may have to do some more searching, alternate spellings, etc,.
to find the town where your family came from.
Slawatycze is in Poland, in Siedlce, which is near Belarus.
It was never in Belarus. Again, check JewishGen.org
I suggest that you further check the town locations and names
in JewishGen, on maps, etc.
Searching Drohiczyn nad Bugieum, Sarnaki Poland