Automation with subitems

Checking to see if this is possible. Ideally, I would like change the status on a subitem in one group (optional tasks) and automatically move it under and item in different group (active tasks). The way I am trying this, the entire task in the group containing the subitem (plus other subitems) moves to the new group. If this can’t be done, I’d like to use the move feature for the subitem, move it under a different task in a new group, and change its status after the move. I’ve tried setting up an automation for that, but I am not getting an automate change. I assume this is because I can only use item. Appreciate any guidance here. Thanks.