Vanity venting

Hey guys, I am moving the vanities in two bathrooms that are back to back. They are basically on the other side of the existing bathrooms. There will be a 6' vanity with a double bowl and the a 36" vanity with a single bowl. I will have a 2"horizontal drain running through the wall between the two. From the first bowl to the spot where the horizontal drain will turn and go into the slab to the main drain is 14 feet. Where the drain goes into the floor is a vent connecting to the main stack. I have plenty of fall in the horizontal drain so that won't be a problem. My question is should I vent every bowl or can I just put a vent somewhere along the drain to handle all three bowls? Thanks.

vent

You may need 2 or 3 vents but without seeing the exact configuration and how the piping could be arranged we cannot tell you which.