in name only
US /ɪn neɪm ˈoʊnli/
UK /ɪn neɪm ˈoʊnli/

1.
existing in title or theory but not in reality
:
•
He is the manager in name only; his assistant does all the real work.
•
Their marriage was in name only; they lived separate lives.
existing in title or theory but not in reality