Bed-Wetting for Older Kids

I have an 11 year old granddaughter that lives at home with my daughter (her mother) and her dad. She has been having "accidents" for as long as I can remember and wets the bed at night pretty regularly. I feel so sorry for her. My daugher and son-in -law think that she is doing this on purpose to get attention or that she does it under stress but she could control it. I am sorry I don't agree with this, I don't say anthing because I love my family dearly and don't want a rift in it. My granddaughters are the light of my life. I am just wondering how you can approach a topic like this and not make someone like my daughter feel like they are being attacked and get them to seek help for her? MY daughter is a wonderful mother she has other children besides this one and she loves them all and they adore their mommy. It just seems to be this one thing that sticks out there and when my granddaughter comes to my house I wake her at night and we go together so there is no problems. Do any of you have any suggestions or sources of help? Thanks!