I think I have a plan now. After making some sample blocks and looking at them, I think I need to trim the 1/8th " off of the panel block. Then add a 2 1/2" sashing to right side and bottom. Add a 2" sashing to the 10 1/2" block. They will both then be 12 1/2" blocks. I will lay some out and see how they look. Hopefully, the difference in sashing won't be too noticeable. This is the only way I can see to eliminate the 1/8" and 3/8" delimma. This has been crazy. Thanks to all who have offered advice. What is it they say, it takes a village....haha!! Still don't know if I can post a picture. I am pretty technologically challenged but I may try when I get some blocks together. Thanks, all!