"Did you all already meet my friends?"
Translation:¿Ustedes ya conocieron a mis amigos?
I messed up this sentence so many times. My brain just refused to process it correctly and I kept trying to write ¿Tú ya conociste a todos mis amigos? Or some variation of that. Weird.
The clue here is the word "all" which has a plural meaning "ustedes" so the correct verb would be conocieron to use.
Write in Spanish:
Did you all already meet my friends?
¿ya conociste a mis amigos?
¿Ustedes ya conocieron a mis amigos?
Ustedes clarified whether you all or they met. Conocieron could refer to either.