I've been locking Mabel and Mippey in a large kennel at night to force Mabel to take care of Mippey. During the day Mabel repeatedly tries to leave Mippey on the book shelf, where of course the little guy/gal wanders off the edge looking for mom. Mippey spends a good deal of time being held and cuddled during the day, typically going back to Mabel only when it's time for her to take on Mom duties, or when they both go in the kennel while we're busy with other stuff or if we have to leave the house. If nothing else, Mippey is getting a lot of socialization and human attention.