Wet Vent in Basement Bathroom

Finishing a bathroom downstairs where the rough waste lines already exist. I live in Michigan, my question is around venting. I have seen AAV’s under sinks in this state before, but it looks like there is already a vent on the sink line. When I put in the waste line for the sink do I need to extend the vent stack higher and put the AAV higher in the wall, or do I put an AAV under the sink after the P trap? Not sure I have seen multiple AAV’s on the same tree before.