How do you deal with the awkwardness of wetting the bed?

My sister is 17 and she wets the bed every night and i'm [16f] i'm getting really sick of it, she pees in the night a lot and she wears pull up nappies which i think is completely gross and the worst thing. She pees during the day too, and she always laughs about it and she always wets herself during the day but at night she comes and jumps into my bed with me and pees literally everywhere i don't know how to deal with it. i try to get her to go to her sleep in her own bed but she gets really upset and i try to tell her to do something about her wetting the bed but she just says thats how it is and i don't understand. i don't think she's incontinent because she can hold her bladder but i just don't know how to deal with it.