Yeah - that's a pretty good idea, really! But then, some people might get the impression that Bob's actually going to be there, possibly to introduce the group and tell a few "a man walks into a bar" jokes, or maybe just sitting in an armchair on the side of the stage, nodding in approval as the boys sing his legacy. I don't see anything wrong, really, with requiring such a disclaimer in advertising or on tickets. Of course, how far do you take it: "Appearing tonight, The Vienna Boy's Choir, featuring absolutely none of the original boys." Well, duh!
I'm not sure if Mary Wilson has an issue with the use of the Supremes' name - seems I do recall some legal squabble a few years ago. I suppose the biggest offenders would be The Platters and The Inkspots, both of which have operated multiple configurations simultaneously. And is it really The Beachboys without any of the Wilson's?