Toddler Troubles

Ok so long story short I have 4 "kids" I own two large dogs and have two human children. Now my biological miracles are ages 3 and 2... My dogs are 7 and 2... That said the absolute ONLY one who listens is my 7 yr old pittie.... I have had some issue potty training my 3 year old as her sperm donor was found to be sexually abusing her ( yes we left and he no longer has any tights or contact with her or her brother) ... I have been working to potty train the two kids and it was going well until the other day. Well I left both kids with my younger brother and his fiance and her 4 year old daughter... They didn't keep a good eye on my son (2 year old) and he got naked and went pee on the carpet. Since then my 2 year old dog is peeing all over marking the carpet and it's driving me crazy. Now my 3 yr old and 2 yr old think its ok and funny and have started doing it on purpose. I have began work on the dog and have cleaned the carpet so many times... Yet the three of them continue to do it and I am at a real loss as I am a sahm and alone with them all from 6am-6pm mon-friday. My fiance has tried to help but he doesn't have any kids of his own and doesn't know much about how to handle this. I have tried everything. Help...