Advice - New Puppy now family of 4!

[Pokemom]

Looking for any advice, we charitably took in an 11 week old female (Abby) this weekend, this is adding to our Boxer family of - Kobe - Fawn, 5 1/2 yr old male, Nina - Dark Brindle, 3 1/2 year old Female and Star - White 22 month old Female. Our 3 we have so far have always gotten along famously but I am worried about throwing in the new one but me and my husband just couldnt turn her away (she came from a local puppy mill and we couldnt leave her there, they were just going to put her on the street).

My concerns are #1 adding another female to an already family of 2 females. No one has started any of the fighting I hear happens so far and our 2 we have right now are pretty calm themselves. They have all been fixed so I am not sure if that has helped at all, but anyone have a functioning family with 3 females???!

Second concern is our alpha male dog Kobe, he never has taken to greatly to any new additions but in the past got over it after a day, isnt the case so far with this one. Any suggestions on easing our oldest male into the new member?

Thanks, Pokemom