Introducing 2 female babies to an adult lone female gerbil

[etsyash]

We have a surviving female gerbil, Etsy, who is almost 2 years old. Her cage mate past away and we were able to get two babies (6 week old and an ~8 week old Females), Snowball and Midnight, from a breeder. The two we got are from the same family and were kept together and already bonded although not from the same litter.  They are awesome.  Our older girl was the more submissive friendlier and honestly our favorite of the two we had previously, so I thought getting two babies might work out for her and I didn't want to get in the cycle of replacing gerbils so I opted for 2.  

I have so many questions. I've been doing the split cage. This is day 4. They are in a 20 gallon tank split and I have been switching them through out the day. They are very curious about eachother and often go to the mesh to touch noses. Etsy has not shown any aggressive signs toward them until maybe last night when I introduced the wheel on one side.  I've kept the wheel out of the cage because I have a niteangel and it is huge!  It takes up so much space, but Etsy is a runner and loves, loves the wheel and really needs the exercise.  She goes so fast and honestly is always using it.  So I put it back and she was on it first.  When I switched sides, the little ones got on it and began to use it, I noticed Etsy staring at them trough the mesh and thumping her feet.  Midnight, the older of the two littles, would then run over to her at the mesh and they would touch noses.  I wasn't sure if the thumping was because Etsy was upset or was she trying to get the littles attention? I don't speak gerbil but I am thinking she didn't like them being on her wheel! Today she doesn't seem to mind it and has been going about her own business. 

I saw a post earlier about someone introducing two babies to an adult female and so I am wondering if any others have introduced two babies to an older adult (preferably female) and if so how long did you do the split cage?

Also, once I introduce them without the mesh, how long should I wait before moving them to a larger tank? I have a 40 gal breeder tank I would love to move them to because the 20 gal split is awful and crammed, and like I said the wheel takes up so much room. I think they would be much happier in a larger tank but I want them to be fully bonded before I do that. Anyone have any experience?

[betty]

This is all usually very straightforward splitting and extremely common: one or two under 8 week olds to a single adult can go very well very quickly. A single pup to an adult goes the best for the obvious reasons and is most likely to last longer than a pair to a single - but the intro itself should be as easy - only when they are over 8 weeks or the intro is left to go on too long can there be issues.

Obviously the state of mind of the adult is also a consideration - and so sometimes double pup intros can be a bit harder as there is more for the adult to take charge of as the dominant one. And of course - they are all females!

The split should be aiming for a week or two tops (otherwise the advantage of the pups being young is lost) and hopefully if your older female is busy running in her wheel and very active in general - she should hopefully just carry on with her own things while the pups run around her getting put in their place every so often.