We used a millworker to get the work done. He was able to reinforce the drawer so it was still usable. The section where the sink is was blocked out, as you can imagine. I wish I could tell you exactly how he did it but I didn't itemize the specifics. Alternatively...not as ideal...is to make the upper drawer fixed.

Thank you for your help, I appreciate it. Do you by any chance remember what sinks you used?

I can add that the top drawer essentially has a cutout that goes around the plumbing and still leaves lots of usable drawer space. The sinks are Porcher.