Hi,
Thanks for your reply .
I wanted to install a new platform because I will create other custom boards with different sensors on it and I thought it would be better to have a platform only with my custom boards.
Managing it like a variant of original Feather works,but I wanted to make it easy to use for everyone, without going in folders that are difficult to reach like the folder "Arduino15". That's why I wanted to create a new platform, if I change my computer or if one of my friend wants to use my custom board we just have to put the link in preferences and then we can upload things on it.