"Kateřina has married sisters."
Translation:Kateřina má vdané sestry.
This sentence could be worded better to make more sense. i.e. ''Katerina has sisters that are married'' or ''Katerina's sisters are married''. As it stands it could mean more than one thing, for instance, ''Katerina has married other peoples sisters''
You can check any other word with the same declination paradigm https://en.wiktionary.org/wiki/nov%C3%BD#Declension and just look for the right ending. Vdané is the plural or genitive or locative singular of vdaná.