I bought a Wilton mold and I dust it with corn starch. Pack it with my marshmallow fondant it does not mold at all. It all sticks and the fondant is all street. What can I do. Don't want to use gumpaste. If I have to UAE gum paste. Can it be eaten?

Have you tried freezing the fondant in the mold, then removing it while it is hard? That's how I do most of mine.

I knead some extra corn starch or a tiny bit of tylose into my fondant, then still dust the mold well with cornstarch before I put the fondant in. You want the fondant stiffer than your usual consistency.

It also works to make the MMF with less water so that it is stiffer...of course if you're covering the cake with the same fondant, making it stiffer makes it more of a chore to roll out,so it's a trade off.

Try to coat the inside of the silicone mold with a dab of shortening. Mix fondant with some gumpaste or Tylose as Texas_Rose suggested and let it harden little bit for 5 - 10 min before using the mold. Even plain fondant works well if not used immediately after kneading it. I never use PS or corn starch for silicone molds, just shortening or nothing. HTH

I always dust my fondant really well before placing it in the molds. I then freeze for roughly 30 minutes and remove it while it is firm.