Thank you, MaG! I'm embarrased to say my 8 year old grandson came by, took a look at it, and said: "Grandpa, there's a pattern here; we just need to figure it out." Five minutes later he had it and, looking afterwards at your solution, he did just what you said. Imagine, 8 years old, and my wife and I with 137 years between us! Fresh eyes...young mind....wonderful attributes...
Robertson