Question: 1 adult axie, can I co hab 2 stunted adults with her?

I've had 1 adult axolotl for 3 years now and she's been living by herself for all of those years. I recently rescued 2 axies off of Craigslist and was told they're a year and a half old but they're growth is stunted. The bigger one out of the 2 stunted is 7 or 8 inches and thin, and my big girl that I had for 3 years is more like 11 and fat. Ive been thinking about buying a 40 gallon for all of them to share, but before I make that investment I want to ask the more knowledgeable; should I? I don't want anyone to get hurt or eaten. The 2 little ones have grown all their legs back recently after about 2 or 3 months of nursing them and feeding night crawlers. Should I try to grow out the 2 more before adding them with my 3 year old, even though I'm not confident they'll grow much more?(severely stunted) Or is it okay to put them all in a 40 gallon with a lot of hides?

i reckon a 40g with LOTS of hides

I just re-measured my oldest, she's actually 10 inches. It's fine to just have a bunch of pvs/abs elbows and planters? I would assume if I keep her well fed like I usually do she wouldn't try to snack on anything else, but I'm still nervous about her with other axies, she's been a lone wolf for a long time now.