Best Friends Sit on Each Other?

I know I've told this story to some people. I was in one room and my girls were in another. I decided to check on them since they were being too quiet. I found Hannah sitting on Evelyn. I almost made her get off, but as I was opening my mouth to tell Hannah to move, Evelyn looked up at me and smiled brightly. I laughed to myself. She was enjoying being sat on. So I left Hannah there. Evelyn loves Hannah so much. She doesn't seem to mind when Hannah does strange things to her. She laughs when she sees Hannah coming and she smiles when she pays attention to her and stops crying when she enters a room. It's adorable!