Housing diffrent finches

I have been hunting on the web for a while and I can not find what I am looking for.

I want to know if you can house Gouldian finches with Society finches??
(same cage)

I have a really big flight cage , and a friend of mine just found out that her Gouldian finches ( over 4 years old ) have eggs. I would LOVE to have 2..
But I can not afford another flight cage like this, nor do I have room for one.
So , I want to know if I can house them together??

Gouldian


Society
(mine look like this -)


I know that society finches can carry a certain bacteria that can effect a Gouldian..
but if you get a RX for an antibiotic ( which i priced , and it is less then 25.00) and give it at the FIRST sign of infection ( watery faces, tucking heads into wings) you should be just fine.
It will rid all birds of the infection and your cage should do well.

I know that you can get Society finches to foster Gouldian eggs. Gouldians should not be bred before they are 2 years old because of their lack of commitment to the egg. All you have to do is change out the eggs of a Society with a Gouldian, and they will raise it as their own.

Now, if they can live together like THAT.. then one would think they could live together with out being foster parents.... yes?

( i would normally call a breeder for this question, but I dont know any )