R3 is your fixed point. The image is blurred, so I'm guessing here: 1.27K with 1% tolerance.
The pot (R1) above is showing as a 500 ohm variable resistor. Your "factory adjustment"?
R2 would be the pot (multiturn) that you "relocated". It reads 5k.
What's the highest temp you can set this to, and what's your target resolution (obviously you've already done the math).
Yes, it is possible to drive 2 * AD5231.
http://www.analog.com/UploadedFiles/...66174AN582.PDF
Where's our EE when we need him anyways?