I am in the process of bonding a trio right now MooBunnay, I might have some ideas. I am far from an expert at this, but I can share with you what I’ve seen and done for my guys.
You are bringing two girls to a established boys? This is (in theory) the easiest one to do. The males should be more receptive to a girl "intruder". So far so good.
Can you arrange a place where the pairs can meet, outside of the boys’ homes? Even a bathroom in a friend’s house would work, just someplace that does not smell like any of the buns. Let the pairs out together in a scary new place, and make sure no bunny hates any other bunny and picks a fight. Some people swear by a long bumpy car ride in the same carrier. At our adoption shows we use a shopping cart with a litterbox in it, and ride the buns around the store. We look for fighting, boxing and biting (bad), indifference to mild interest like sniffing (good) or serious interest (mounting, grooming, snuggling, very good). Mounting is good if the bun on the bottom (not always the girl) tolerates it, bad if that bun hates it and fights back.
If the buns are agreeable, they need to be housed within sight and smell of each other for a while, but separately. After that, it just requires time and patience to keep the buns together in neutral territory in the boy’s house and see how it goes. I was lucky, DJ and Curly Sue bonded in a week. Making the trio has been a bit harder.
Good Luck, hopefully 2 down 24 to go!