I recently encountered this expression and I'm pretty much stumped. People seem to be using it in place of "who". Example:
[...] they were developed by non-medical professionals whom of which have applied their skills to help solve a health care / medical problem they had faced.
As well as Dave, special thanks goes to the 'Girls in Pink' for providing a high service throughout the whole day, as well as club chairman, Bob Thomsett and Chrissie whom of which manned the kitchen which was busy all day.
I can't quite wrap my head around the expression, but I figured it might be one of the many idiosyncrasies of the English language. Is this a valid expression or some newfangled bastardisation?