I guess no one else wants to tackle this problem:

Under the IRC a lavatory is rated at 1dfu and an 1-1/2" line is rated for a maximum of 3dfu's so you may add the two additional lavs on that same vertical drain line However, you MAY NOT add them in the manner that you have illustrated.

Under the IRC the bottom of the fixture arm at the trap may not be higher than the top of the fixture arm at the vent opening, therefore the vertical offsets you have illustrated are prohibited.

The solutotion is to remove the existing sani-tee and replace it with a sani-cross (double sani-tee).
Careful here, make sure you use a sani-tee because a wye & 1/8bend or combo would be prohibited. (See Illustration)

With the sani-cross in place you now have two options.

OPTION 1.
If the center to center distance between the sink drains does not exceed 30" you could use an "End waste connector" or "Center waste connector" and attach both sinks to a common trap in the same manner as installing a double kitchen sink. That trap could then go into a single fixture arm to the stack.

OPTION 2.
While it is prohibited by the UPC, the IRC will allow two traps to be connected to a common fixture arm.

Solution: extend the fixture arm out from the wall to a point midway between the two sink drains.

Install a Double Wye then install a "Street 1/8 bend" in the side openings of the double Wye and a Female thread adapter on the end of the Wye.

Now install a section of pipe and a trap adapter on each side opening as illustrated

(NOTE: When a fitting is listed as a "street fitting" it has both a male and female end. You can install the male end directly into the previous fitting to save space)

Install a threaded plug in the female thread adapter to make a cleanout.

Thank you very much for your reply and explanation.

After opening up the floor to look at the supply lines I want to tie into, I quickly realized I was out of my league. I ended up hiring a plumber and contracted with him just yesterday.

Thanks again though.