I have a question along the same lines. I’m new to the raspberry pi. I just started mine up with the noobs sd card that came with my kit. I installed 2 os’s. Raspbian and openelec. I would like to know if someone could point me into the right direction on how to now add retropie to the same card. I don’t mind if I have to reformat or start over but I would like to be able to start it up and choose between raspbian, openelec, and retropie all depending on what I want to do at that time. Like I said, I am completely new and would appreciate any help. For some reason, I couldn’t figure out how to start my own topic on the forum.