Maybe pregnant again

Dappy had babies about 4 weeks ago. I removed the dad that same day and he was neutered 3 days later. Anyhow, all the bunnies have finally been reunited and doing well. Tonight when I secured them in the top house for the evening, mommy (Dappy) started digging in all the bins, like nesting. Should I be worried that she might give birth tonight and if so will the new babies be harmed by the bigger ones?

If the dad bun was still with mom after she gave birth the first time, then it is possible that she could be pregnant again. They can get pregnant immediately after giving birth.

If she has babies again, you will likely need to wean the older babies from mom, as the newborns won't be able to compete with them for her milk. It's not ideal to wean at 4 weeks old, but if you want the new babies to have a chance of surviving, then it has to be done. If you have to do this, it's best to minimize stress by keeping the 4 week old babies in a familiar environment. Also feeding plenty of grass hay to them is helpful, and not feeding sugary/starchy treats. Baby buns digestive systems are very vulnerable at this stage, so you want to help keep their digestive process as healthy as possible.

I honestly think they might already be weaned as they don't follow her around trying to get food like they used to and when I feed her and daddy leafy greens they attack the food and hay and pellets. I have been watching for soft poops and diarrhea and haven't seen any. They drink out of the water bowl as well. Would it harm them to just take them out of the cage at night and bring them inside while leaving mom and dad outside?

I would not recommend keeping both litters in the same area. The newborns can get hurt with the older ones around. Normally you would leave the older ones together in the cage they spend their time in and set up a new area/nest for the newborns, that they can't get to. This all assumes she does have a back to back litter.

Thanks for the advice. I am hoping she doesn't have back to back litters. I did move the 4 week Olds out for the overnight hours and added more bedding and hay to mom's nesting box. I will check things out in the morning and if no babies put the babies back in the cage during the day. There is no way to keep them out of the nesting area, while still letting mom go up there. But so far no babies. (And yet I didn't know where was pregnat the first time. However, we have found great homes for 4 of the 7 and will send then to their new homes in a few weeks.