What would you do?

Ok so I have a 4 year old neice and a 9 year old nephew. Both pee and poop them selves still. Well today my neice pooped and I changed her. She had a horrible and I mean horrible rash on her front and back. It's do bad she had blisters on her little flaps and sores on her butt. Her mom don't put underwear on her either. I of course put my son's diaper rash cream on her all over. It hurt her so bad just to have it wiped let alone me touching it to put cream on her. I sent her the tube I had home with my mom became she watches them and I know she will put it on her. I tell her grandma has some more for her so she will feel better. My nephew heard me and asked if he could use some because he's sore and his balls hurt really bad. I just don't know what to do. It hurts just knowing they are hurting. How can a mother let her children hurt like that. To top it off she's trying for baby #3 since I had my son who's my first. My son don't need and of the cream I'm half tempted to just give my nephew a tube so he has his own.

He was never really potty trained she was but when you live like that I guess you just get use to going on your self. It's very sad.

My mom noticed but didn't know what to do to help them with the rash. She don't drive so she couldn't get to the store to get them anything. She's tried to get them to go to the bathroom but she's just to sick to fight them. I have tired also but they just refuse to go and im not with them all the time. They're not being touched we would know. They're parents are just lazy so they don't put the time in to teach them. She my nephew had trouble with going #2 since he was born. He couldn't tell when he was going but now he can he just got use to going on himself. My niece is doing it now because he can do it so can she kind of thing plus they moved out of my mom's to there house so it was a huge change for her.