"My daughters and your brothers are sleeping."
Translation:Filiae meae et fratres tui dormiunt.
latin is not like english. in english, there is two present tenses. one of them is simple present and the other one is simple continuous tense. but latin has only one present tense (tempus praesens). so you cannot use "sum" and its inflections as a copulative word to build a present tense.
I placed the possessive adjectives in front of their respective nouns and was marked wrong. I thought that meus and tuus were on the list of adjectives that more commonly precede their noun rather than follow it?
actually none of them are wrong: the adjective can precede the noun or vice versa. but in usage, possessive adjectives as meus, tuus, etc. mostly come after the nouns.
Duolingo should accept present active participles i.e dormientes sunt
No, that's bad Latin. "Filii dormientes sunt" would be understood by anyone not stuck thinking in English to mean "there are sleeping sons" or "the sleeping sons exist" or "they are sons when they sleep" or "the sons are sleepers", etc., none of which are very plausible statements.