I feel for you. My older dog pees everywhere. My vet says it is a behaivor thing. Jealous of the other dog. Wants to be dominant over the other dog. Marking his/or hers territory which is you and your husband. will continue doing it forever. you need to cage when ever you can not be in the same room with the dog and watching all the time. also take dog out on a leash to go to the bathroom. also if you see him/ her start to smell or want to mark make loud noise he told me to shake a can on marbles and say NO Bad Dog put in cage he said do this for six weeks to break the habit!!!!!!!! I try but too much trouble for me to keep taking out to bathroom on a leash. good luck. by the way is it a boy dog that is doing this? read your post again. He is a boy and the little one is the girl. Same at my house. Littleone is boss, definately a behaivor thing just like mine. It's really hard to stop. I close off all the doors I can. and do what the vet told me too but the bathroom leash thing is hard for me to do. He said that if you do it for six weeks it should work but if he pees again you have to do it for another 6 weeks!!!!