Advanced operations are good for parenting posts.
Steps:
1. Choose a thumb (blue background when chosen): Other thumbs will be compared to the chosen one if they are the same ratio (green background, if post is better and red background if post is worse). A post is better if: bigger size and if same size, the older post is better.
2. Set other posts as child or parent as the chosen thumb. Better post should be set as parent and worse post should be set as child.