I would be worried about territorial disputes - the cage you have right now is your two girls' "territory" and any new budgies, even a male, would be "trespassing" in their eyes. Do you have another cage you could put beside your girls' cage with the new ones in it, just so they could get used to each other before putting them in the new cage.
Also, if you do put them all together, I would take your girls out first, rearrange the cage so it looks "new", than put them all in it at the same time - new territory, no one needs to defend it.
Good luck! I hope this helps
Also, if you do put them all together, I would take your girls out first, rearrange the cage so it looks "new", than put them all in it at the same time - new territory, no one needs to defend it.
Good luck! I hope this helps