Hi a33ik
first many thanx for all your answers. I'm not so many time that work with D365s (a few months) and I'm not so practical.
The 2nd approach seems better and more understandable than the 1st, for me.
This is my scenario: in my company sellers want select from a restricted list of users (inserted in the USERcustomized) and want activate acces to opportunity to the user selected with a Yes/No button.
So I must create a flow that insert from the list in USERcustomized to principalobjectaccess, all the users that have button in yes mode.
This is beyond my knowledge.
Can you help me with an example?