Congratulations on your new additions
Sorry but you will not be able to keep 2 pairs together in one cage. For starters you would end up with females having kits every 111 days which can lead to all sorts of health problems for the poor females and their offspring
Caroline has already mentioned one; malocclusion
I would suggest you phone around and find an exotic vet with experience of castrating males as a matter of urgency, you will probably find the females are already pregnant so your numbers could rise quite quickly in a few months .
After the males have had the op you need to keep them in a separate cage next to the female for a minimum of 8 weeks until they are no longer fertile.
You single male kit needs removing from mum at the age of 8 weeks, they have been known to mate with a female as young as 12 weeks so please dont take the risk of inbreeding.
There is alot of conflicting advise on the internet unless you know where to look. However you would be more than welcome at
ChinsRus - Chinchilla rescue and forum where we have members with many years of experience of keeping chins .
Chins are adorable, inquisitive animals and once you have learnt more I am sure you will do the best by them
I have had chins for 12 1/2 yrs and rescued for 7yrs now so If I can help/answer any questions or steer you in the right direction please feel free to get in touch