Many thanks to everyone who helped me to identify the mystery cast-on method in the previous post.....I've come to the conclusion that it probably is the "combined two-strand cast-on"  or a variation of this method. There doesn't seem to be any online tutorial for this cast-on...yet! If I can enlist the help of my sons perhaps there will be one soon  Will keep you posted.............Thanks again and hope you all have a terrific day!