I have 2 guniea pigs both nearly a year old and they get on great and live with my rabbit and all get on fine.

but i have just got 2 more g pigs both the same as my other 2 but are 9 weeks old and i have tried to introduce them but my 2 older g pigs just ganged up on the smaller ones and tried to have with them even tho they are all same ! so they now live in different cages but now my original g pigs have kinda been fighting and really grinding their teeth and when they hear the 2 youngsters squeek they go crazy in there cage! do you think they can ever live together or shall i just keep them appart?