Gentlemen:
I REALLY appreciate your replies!! Looks like my best starting strategy should be to use one Power supply and just Fixed 1 & 2. I have seen diagrams and text for passive mode in Barry's books and elsewhere. If there is confirmation that Variable, set to Fixed, will work with DCV in passive mode, perhaps I would use one power supply for Fixed 1&2 and the other power supply for Variable 1&2 set to Fixed. As you might guess, I always do things the hard way.
Thank you and Happy New Year!!!!!!!!!!!!!!