Can we put an existing borrower who is an appraiser on our approved appraiser list and use the individual as an appraiser?

For his own loan? Or in general?

we have appraisers with credit relationships, would not engage them in a conflict situation, and if memory serves me, we report the credit relationship at exam time (safety and soundness).

you are fine as long as you don't give him/her a better (or worse...hahaha) rate because s/he's on your approved appraiser list.

The appraiser must be independent with respect to the transaction being appraised. If the appraiser's individual credit relationship with you does not in any way influence the valuation, then using that appraiser should be OK. However, you must be able to demonstrate the independence. Regulators are currently looking very closely at this because of rising rates and dropping home values. So the best practice is to use an appraiser with no connection to the bank.