Although most of the time I had three, I've had as many as four, all females (as the result of serial foster fails :D). I fed them all at the same time. There were no squabbles or attempts to steal another hound's food (although it did require the occasional verbal reminder). Walking four could be a bit of a challenge with two leashes in each hand. Fortunately, I have a fenced in yard, so most daily walks weren't a requirement.
They all got along, but one thing I did notice. They seem to "pair off". It was something that I didn't notice that much until I went back through my photo archives.