Isn't that collaboration for the interface? Not the chess engine.

https://www.chessprogramming.org/Mephisto_Mondial
"and short later the DOCCC 1985. Nona was ported to Ed Schröder's faster interface code for the Mephisto hardware"

Here as well: https://www.chessprogramming.org/Nona
"Frans ported Nona to Ed Schröder's faster interface code for the Mephisto hardware, and Ed, not competing with Rebel this year, was even mentioned as Nona's co-author for that 1985 tournament"