My two older ones are male and female and I got a second female. It worked out well, because my GSD is very good tempered and the older female is about 7 years older then the GSD. I will add a fourth dog and it will be a male. I won't push adding a third female. All of mine are good tempered.
Misty- Samoyed Mix
Tannor- Golden Retriever CGC
Robyn- German Shepherd CGC
Cats-Thunder, Harley, Miley, Bandit, and Ferah
RIP Boo..Black Lab
"A dog is the only thing on this earth that loves you
more than he loves himself."