I keep a yearling and a 2 year old, and a 3-4 year old together and have no problems, but that's not to say there isn't any problems with keeping snakes that are larger than each other together. With Mama, she's been very slow lately and will sit in one place for up to 6 hours at a time before adjusting herself, so she can't technically crush Thumbelina. Mama is probably 20 times the size of Thumbelina, and 4 times the size of Runt. Runt and Thumbelina love to sit on Mama's back while she's sleeping.