Good idea to design go back button in modal

I need some directions, currently I have a list, if I click one of the items, one modal is shown with information about the item previously selected, and a list of its children, so if I click one of its children the modal information is updated, I mean, the modal shows information of children previously selected, so in the modal I have a button that close it. I just want to change that button to go back, so if I click go back the modal information will update and show previously information, I mean information of parent....

Have you ever encountered this problem?