First of all if it’s really affecting her self-esteem, pride, and social life, it isn’t likely that she is doing it deliberately or out of laziness. It sounds like she spends only part of her time in your home and the rest with her mother. It would be difficult to try something like an alarm that would only be used a few nights a week at best. You might try getting her doctor to prescribe medication like DDAVP and try it at your home, then if it works ask her mother to use it as well. It might help to find out if either of her parents were bedwetters as it is often hereditary, and if so you might expect her to outgrow it at about the same age that her parent did. That might also be useful information to share with her doctor. You may have a tough time resolving this problem on your own, you need the support of both her parents. Without her mother’s support your options may be limited to trying medication (at your house only), using diapers, or just washing lots of sheets. Try not to put too much pressure on her – if it’s already affecting her self-esteem, then being told that it’s her fault or that she is just too lazy to get up will only make it worse.