ihi Julien,
Its an easy task indeed, you won’t need any code.
What you should do is follow this
This way you let members add a form to a collection.
then you should make an member page and do olmost the same.
You add the needed fields (textFields)
and a button (Update button)
add a dataset (your form collection)
and link the needed textfields to the dataset.
Then link the button and let it update instead of inserting.
Kind regards,
Kristof.