That is a little tougher. I expect someone else will come up with a better solution than this. But give it a shot and let us know if it worked. I don’t know what your ?: does so maybe that could replace my mess. The mess of stuff I used is supposed to match all reasonable characters but pipe. I took the ^ out of it.
Exact match
rPID(?:[^|]*|){5}(MUELLER^)
MUELLER somewhere in the middle
rPID(?:[^|]*|){5}([A-Z,a-z,0-9,/,-, ]*MUELLER[A-Z,a-z,0-9,/,-, ]*^)
I don’t think you need the parens around MUELLER^. I left them in. You need them around that first bit so the {5} is applied to the whole group of things in the parens.