Which country do you believe they may be living in? Which country do you live in?
I would think that your half-brothers' family name would end with an 'o' (Masc.), and your half-sisters' would end with an 'a' (fem.). 'Sz' (Polish); 'Sh' (Ukrainian).
p.s. I am sorry, but I made a spelling error in my previous message.
Correction: Шапірo = Shapiro (Ukrainian); Szapiro (Polish). Шапіра = Shapirа (Ukrainian); Szapirа (Polish).