The 'concerned members' or the members concerned', which one is grammatically correct?
Actually, the second option:'the members concerned' is correct.
In the first option, the word 'concerned' is functioning as an adjective, which may mean 'worried' or may say that the members of some organisation are feeling much concerned about something that has gone wrong.
But the word 'concerned' in the second option, is a part of the participial clause: the members who are concerned or related/responsible to some work or task already given to them
Usually, the first option is used. But a person who knows the grammar shall always use the second one.