Proximal praise is when we praise one child in order to get another child to do something. Children will work hard to get our attention and can get quiet jealous when we give it to others. Try using this to you advantage!
For example, my daughter hates brushing her teeth, so I really notice her brother and give him lots of attention when he is brushing his. Most of the time, she picks up her toothbrush and follows suit. She loves the positive attention she gets as a result!