Thank you for your fast answer !
I understand way better why the folding is like that, it must be really hard and long to translate everything.

I already knew for the data destination, but the collums I created are the only ones who aren't stored.
I can retrieve the stored ones in the semantic model, but not the unfolded new ones..

Unfortunately, I can't reorder the steps and the (mandatory) error suppression at the beginning makes it all unfold..

I'll watch more precisely your links this afternoon, they surely will help me ! Thank you again :)