"We have never seen some of our son's girlfriends."
Translation:Některá synova děvčata jsme nikdy neviděli.
You can do many different word orders in Czech language. The word order is very free. The word themselves do not change however. "Nikdy jsme neviděli některá synovA děvčata." is a perfectly cromulent Czech sentence and the meaning is the same as the original but you stress a different word.
Your word order stresses "nikdy" and the original stresses "některá" or "některá synova děvčata". You often decide according to what is already known and what is the new part announced by the sentence.