Hi LiveLaughLove. You are wise not to spank. I am not sure how rewards go.

What about having the 6 year old clean up the mess or wear pullups or whatever you call 6 year old diapers. That way it is her choice. Girls usually have big bladders. It could be a urinary tract infection or a psychological issue to attract attention from mom.

Other suggestions. No water or fluids after 5pm. must pee before going to bed. Wake up in middle of night and have them go the bathroom (might not be good idea for yours or their sleep.