I hope you are planning on placing the two new ones in a different room for awhile(30-90 days). Its called quarantine(QT). If they are not sick the one you have may be and could make these two sick.

Housing them together can be done but it is not generally advised. The male will need to be separated so he doesn't kill himself trying to breed. I think you have a lot to learn before you even start thinking about breeding right now.

Was this clicking only before the shed? If so it could have been caused by the up coming shed.

If it is RI we need more info. What are the temps you have been providing? What kind of thermometer are you using to track them? If it is an RI you really should plan on a vet visit to get a culture done so it can be properly treated.