Good morning Grace -
That's a beautiful quilt, it will be lovely, your gift will be a wonderful creation and have extra special meaning for your son and soon-to-be-ddil. By loving and supporting them in their life together, you are contributing more than you can imagine to their happiness, I'm sure. Especially considering what a flux your life is in right now. Will the signatures be part of the top, or the back? Will it be in the colors of the wedding, or another colorway? When you have the pieces ready for signature, will you have extras (in case people make a mistake etc.), also a picture of the quilt pattern, so they'll know how it will look when it's done?
Your gift will be wonderful, enjoy the happiness of the coming nuptials and love them both - it will only get better and better for you as you go forward, trust me, I've been there and life is so much better now than I could have dreamed it would be back then.
Hugs and happy thoughts for you!