I spray computer printer paper with that cheap $.96 clear spray from Wal-Mart to stiffen and waterproof it. The only problem I've found is that I tend to spray a bunch and it yellows my stuff a little. You might try thay for the fabric also. You can compensate for yellowing by choosing coordinating colors that aren't as bright or more off-white.

There is a stiffing for material, I have sprayed bows and lace with it and it stays pretty stiff if you use more then one coat, dont know the name as I had to change the bottle and threw it away. I used varnish to seal some saltdough ornaments that had small bows on them, they got real hard but didnt look very nice, you might try liquid starch on the material parts,try the varnish on a scrap piece and see how it looks, maybe someone will have another idea for you
oddie

Check Joann's - it's called "Stiffy" - works fantastic on fabric.

Sal