SAS my breeder strongly discourages 2 females in one household. She will not let her retired cats go into a multi cat household if their personality is not suitable and will not sell 2 females to the same home. Although she says sometimes it does work out you can never tell, especially with Abys. I'm thrilled Maya has stopped peeing on me and my stuff, Bodhi is starting to stand up for himself. My parents living in the household have been accepted by the cats and why not, lots of attention , games and treats. Sort of harmony for now...I'm enjoying it. I wouldn't dare introduce another cat of either sex. Abys.. my previous 2 were a lot more mellow, but not such - - - - disturbers.
I do think your Miley and my Bodhi would be a good personality match and Graemer and Maya...well would the house still be in one piece. I'm sure Gabe would be smart enough to keep his paws out of the fray.