If you are asking how to plumb two lavs without siphoning the p-traps, then the answer is to pipe each lav with a separate p-trap and trap arm, each one vented in the wall.
Does the wall need to be opened up? Yes.
The method you have been asking about does not meet any plumbing code I know of.
If you don't want answers from plumbers, then maybe you should have posted it at a true DIY site and a homeowner can answer your question with,
"I work on computers, but sure, everything works."
I'm pretty sure that in other fields, not everything works.
I'm pretty sure that that they have classes and eduction for every job.
Plumbing requires an 8,000 hour apprenticeship.
We're trying to save your bacon with some quick answers, but you don't like hearing that the wall needs to be opened up.
Plumbing is simple, right? That's why they require only 8000 hours, class lessons and then a State required test and licensing, followed up with plumbing permits and inspections.
Right now, get on the phone and order a plumbing permit like the rest of us.
Then you can ask your local plumbing inspector if what you are doing will pass "his" inspection.
We give advice that will satisfy a plumbing inspector.
If you don't give a rats ass about permits and inspections, then don't bother posting.
There are other sites out that there will pat you on the back and tell you that everything works.
Not everything will pass inspection, not everything will drain when you are done, not everything will prevent siphoning of the p-traps, but anything can be done.
Not everthing works in real life though.
I love it.
And this is as easy as it gets.
We even had a picture to show you.