Select one duplicate answers restriction in a repeated group

hello , how can i create a constraint for a select_one question inside a repeated group as if you chose the name for the first family member inside the repeated group you cant chose it again in the next repeat

Have you gone through our post discussed previously? It should solve your issue:

That is great thank you !
but it works for me only on the first loop of the repeated group on the second third loop i can chose the first option again how can make it valid for all repeated loops ?

The approach outlined in the post discussed previously enables you to enter a response only once. If you select the same response in the second repeat it will flag you an error message. So basically, this method allows you to make a unique entry of the response within a repeat group.