I have never had any fighting when re-introducing does back into the group, they are very good at excepting does back, but I think it helps if the does taken out have been established in the group for a while before they leave. I re-introduced a doe the other week and the others just checked her over and then got on with what ever they were doing before
I havent had to do that yet, all my does are in one large cage, the bars are too wide for young mice so havent been able too put mum and baby does in together at the same time I have always put mum back first (when she is no longer feeding babies and babies are not relying on her) I have at the moment 2 does waiting to go in when they have grown a bit more, their mum is all ready back in the main group so am hoping all goes well when it comes to it
We normally re-introduce mum and her babies to another group when we have to take bucks out so at 4 weeks and never had any problems, we have in the past introduced at around 3 weeks so i don't see why you cant put your mum and her pups with a group
I wouldn't recommend introducing mothers with unweaned babies to other adult does as the mother may feel the need to protect her babies from the strangers. There is no need to do introductions at this stage anyway - wait until the baby does are 5 weeks old if you must intro mum and babies to a group.