It all depends on the fish. I've had 3-4 in a 10g with little to no problems, or at least nothing more than chasing & nipping onoccasion. When I had 5 little ones in a 10g there was even less aggression even as they grew up. Now I have 9 in a 46g.
In short, yes. Many others on this forum have done so with no problem. You might want to watch when you are adding more females as it probably will reset the hierarchy statuses. I even included a male in one of my sorority tanks, and it's still fine. Keep in mind each male is different, some are more aggressive than others. Good luck.
P.S. GOTTA CATCH'EM ALL, GOTTA CATCH'EM ALL, POKEMON! Loved that childhood show!
P.S. Dang it! Shellieca you beat me to it again lol.
If you're going with 4 adding one more wouldn't be a big deal. I found with a 10g that I had better results if they were added at the same time. BUT the last time I bought 5 & put them into a QT 10g before adding them to my 46g 2 of the girls fought like I'd never seen females do before. I took one out & floated her in an opaque dish for a few hours then added her back, they had a stand off but then settled in with no further problems. I just recently added 2 more girls to my 46g & the one new girl is chasing all the other ones & she's 1/2 their size, it appears she is now the one in charge.you just have to watch & be prepared to take action if need be. IME there will always be some chasing maybe a little nipping but not usually anything more serious.