The bar sink also needs a vent.
Venting the lav does nothing for the bar sink.
Here is a nice link to Bert Polk's plumbing tips
The vent is above the trap arm for the bar sink.
Where does a vent for a sink need to be? We have a basement bar sink that will be tied back to the main drain 7 feet away. At the tie in point to the main drain is the vent stack shared by the bathroom. See picture below. I am just wondering if the current vent stack is enough for venting the bar sink or does it need a separate vent?