I have 3 at 4months, can I add one

[lbsimm]

I have three that are almost 3/4months. Can I add one more if I get it the same age? Add it at night?

 

[lightchick]

I think it should be ok. If you can let them see the new one but keep it separated for a day or so, and then you could add the new one at night. I'd do it.