If I make a shahakol or hadama then decide to wash. Do I first make a borei nefoshos or can I wash and be yoitze with bentching
A Borei Nefashos should be made first.
See Mishna Brura 176:2 and Shaar Hatzion s”k 8.
cf. Biur Halcha 174:7 sv. Veafilu, who brings opinions that if the foods are eaten during the meal as well one would not need a bracha achrona. see Shaar Hatziyon s”k 5 who rules against this opinion. see also Igros Moshe O:C 3:33.