Thank you all for your very helpful replies (including pms !). I'm glad to read from you again too !
I guess we have got what we need to settle the issue as far as the authors are concerned, however the question of possible publisher
rights remains somewhat obscure to me (so far): D. Dykstra apparently claims (and
obtained in 2015) copyright ownership on Ray's works, not on
other Commentary Press publications... (in France we would distinguish
between author's and publisher's rights, I have no clue how it works in
the U.S. -- not to mention what were the initial contracts, and if the
potential rights were transferred to any successor of Commentary Press as the publisher)...