Little brother peeing through goodnites

I hope it's okay that I post here. I'm not a parent. I just have custody of my little brother because my mom is useless and his father is not in the country rn. If I need to take this down I will. I have custody if my 14.5 year old brother. My boyfriend also lives here. It's a bit uncomfortable for him because he is kind of afraid of most men and afraid of older women. I'm 26 so I'm not old but my boyfriend is a man and my little brother is very uncomfortable with him. My boyfriend said if he needs to move back home with his mom for a while so my brother can get situated he would. I feel bad kicking my boyfriend out of a place that's his home too but it might have to happen. So my brother pees the bed at night. Went to the doctor. It's nothing medical. Most likely just trauma. He wears goodnites to keep the bed dry and his skin, because he already has skin issues and having pee on his skin just irritated it. He has plastic sheets on his bed. Last week he started leaking through his goodnites. Idk why. He doesn't have anything to drink 2 hours before bed and he always goes pee before bed. My auntie recommended baby pants (those plastic pants you put over diapers and pull ups), but idk. She's not a mom but she is a nanny. I just wanted some advice from parents first and again sorry if I can't post in this group.