I made my marshmallow fondant too dry. How can I fix it?

I made marshmallow fondant for the first time. It is now resting in the fridge and I am going to roll it out tomorrow (after putting in the microwave to soften a little)...but I am pretty sure I added too much powdered sugar. I only used 10 oz of marshmallows, and I thought I was working with 16. I stopped kneading in sugar when I realized this, but by then the fondant was pretty hard. Is this worth saving or am I better off starting again? Id love to make rolled fondant but I live in a small town and cant find glycerin to save my life and I don't want to buy fondant...so marshmallow is the best option. Any advice? I read I can loosen it with crisco but will that make it taste terrible?