4 weeks is too young. They should be left with Mum until at least 6 weeks.

What is happening with Sage - are you going to get her a companion? She will be awful lonely on her own

I just removed my two 7 week old female gerbil pups from their parents (dad is neutered) to put them with a lone rescue adult female (who is 1.5 years old) and the parents seem rather sad without them - I thought the Mum would be pleased to have some peace and quiet!! The babies don't care because they have a new Mum!!