In light of what Hissy said (who happens to know a heck of a lot more about ferals than I do) and the more I think about this situation, I believe you should keep the kitten. She has too many obstacles against her if you release her. The mom cat will likely not care for her, and as Hissy said, may run her off, making her situation even worse. The kitten has no shelter outside that she's accustomed to using. And when you move next week, she'll no longer have food. Re-reading your comments about how comfortable the kitten is being indoors now, and how happy and content she is... It doesn't seem right putting her back outside in the middle of winter. Mary, I know you are agonizing over this. But do you really think YOU'LL be ok once you move knowing that the kitten is alone outside with no food?
The timing is bad because of all the stress you have with the move. But I think you (and Levi) should try to make the kitten a new family member. Lots of us have done this too, and can help you. You care very much about this kitten and thanks to you, she has already made progress. No one can predict how the relationship between the cats will turn out. Rarely do cats react so badly to each other that a new home must be found for one. More likely, at "worst", she and Levi will just tolerate each other. At best, they will become good friends who will keep each other company.
The timing is bad because of all the stress you have with the move. But I think you (and Levi) should try to make the kitten a new family member. Lots of us have done this too, and can help you. You care very much about this kitten and thanks to you, she has already made progress. No one can predict how the relationship between the cats will turn out. Rarely do cats react so badly to each other that a new home must be found for one. More likely, at "worst", she and Levi will just tolerate each other. At best, they will become good friends who will keep each other company.