I was having a similar problem with Bandit, but it had to do with potty training mainly well since he is a boy we got him wee wee wraps from yougetthesmiles....maybe if you can get the two boys not to do it then the girl wont either....I dont know i'm not experienced to tell you but its a thought....here is the thread to yougetthesmiles....she might be able to help you out and give some advice also....
http://www.yorkietalk.com/forums/yor...et-1-free.html