I am replacing an acrylic tub with a walk-in shower. The tub’s 1-1/2” drain is centered ~3-7/16” above a concrete floor slab. The drain is fed into a 2-inch no-hub cast-iron P-trap (Charlotte EZS 10) in a common wall between two back-to-back bathrooms. Of course, I need to match the elevation of the existing P-trap inlet, but with the lowest-profile commercial clamping drain I can find (KBRS SO-42281), I still end up with an approximate 9-inch high shower curb. This is based on a dimension of ~3” from the upper surface of the drain’s bottom piece to the center of its outlet (see attached drawing for details). Of course, I would like to reduce that step-in height as much as possible, so my thought is that by combining a standard Oatey 42314 clamping drain with a Charlotte 2” ABS 706-X Solvent Weld P-Trap I can get the outlet higher (1-1/2” vs. 3” from the upper surface of the drain’s bottom piece). This will give me a more reasonable 7-1/2” curb, plus it will reduce my pre-sloped bed mud requirement by approximately 1.7 c.f. Clearance for the P-trap in the concrete floor slab will be needed, but that’s not difficult. Basically, I am adding a second P-trap to the one that’s already in the common wall. Q1. Does this violate any 2019 Uniform Plumbing Code requirements? Q2. Would it introduce any other issues that I should be aware of?