Since I was curious (and not very familiar with Resident Evil), I just looked up their ages. Assuming this picture is taking place during Resident Evil: Revelations 2, then Claire would be 32, Sherry would be 25, and Moira would be 20.
Also, this is missing an artist tag - the artist is "demonfencer", who's also drawn a bunch of Elsa x Anna art on her Pixiv.
i just bought the doujinshi compilation of this! It has a lot of cute and short Chika x Riko, but it also has Aqoura playing real life Splatoon with ChikaRiko having a lover's quarrel.
iirc, Claire met Moira before RE2 because the Redfield duo used visit Barry often, Sherry is technically the 2nd or even 3rd on the immouto line.
They should just make a Claire sandwich imo