I remember a rule Jenny Beyer made when using a special border fabric. Put the odd cut in the middle so the ends would match up and sure enough no one notices that odd cut. I have the same dilemna for a pieced sashing with diamonds in the center. I couldn't get them to come out the length I needed so decided to add an odd sqaure/diamond in the middle of the length of smaller diamonds. Or I could add a corner square also. Haven't gone back to that project yet but I now know those are 2 solutions I can use to fix my problem.