Thanks to everyone who responded! You've given me a lot to think about. My plan of action is to quilt down the center of the brown sashing to help stabilize it. Then I'm going to try an all over meander in thread that matches the muslin. I think my fear was that having the white thread cut through the brown sashing and the greens and yellows would ruin the geometry of the quilt. However, I've been looking at how similar patterned quilts have been done & it looks good, so I'm ready to take the risk. I will post a picture when I'm finished.
Thanks for the encouragement and support!
Krista