bedwetting boys age 9 - 12

My nephews are age 9 and 12.  They still sleep in diapers.  My sister says the pediatrician is not concerned and says this is normal???  - just need to stop drinking early in the evening and wake them up in the middle of the night to go to the bathroom.  They are embarrassed, can't stay over at friends.  What can we do?  We have tried a machine that clips to their underwear and vibrates when it gets wet.  Any suggestions

[margypops]

Not much if their mom thinks its okay... she needs to remove the diapers ,they are far too old ,  drinking a lot particularly soda in the evening will make them use the bathroom more. If they are embarrassed it means they don't like it, are they in 2 seperate beds and they each wet the bed at night?