Originally Posted by
MTS
I guess, depending on the method the OP is using to make her braid, you could eliminate trimming the outside FB edge straight until AFTER quilting.
Leave it be, layer the quilt sandwich (basting with spray, pins, thread, whatever) and quilt.
Then trim the edge straight.
You could also attach the inside edge to the quilt center first - pinning heavily to position correctly - and then trim the seam allowances.
This is what I did for the quilt below. In fact because I had just a few inches of extra fabric, I didn't trim it until after it was quilted and I was ready to put the binding on - even though I wasn't working with bias edges (they are strips), the theory is the same.