Subitem status change

I have a board where individual subitems may need to be marked as ‘complete’ or ‘not required’. If either of those things happen, I need the subitem to be moved to another group on the board. Currently I can only get the whole item to move based on the subitem status, but I need only that 1 subitem to move.
I want the subitem to stay linked to the main item however, so envisage the automation duplicating the item, then moving only the relevant sub item to the required group