I think it's fine not to SID the quilts. Think of all the millions of quilts that were done with an edge-to-edge design. None of those have SID. I agree, that the absolute best option is always to SID everything but I really think that making 2 quilts without SID during the time it would take you to make 1 perfectly would be more appreciated by the charity. I do SID the borders just to try to keep my quilt square/square-ish, but that's the extent of it. If I weren't doing a different motif in the border(s), I might even skip that step -- not sure. I have no doubt what you do will be beautiful & cherished for many years to come by whomever receives it.