I made MMF on Sunday evening to go on my cake that I'm entering in a contest this weekend. I think I must have overcooked the marshmallows. 
I didn't put enough color in it so I was trying to knead it in last night but the MMF was much stiffer than it was the first time. I had to keep reheating it to make it pliable enough to work the color, it's still not worked in good, as soon as it started cooling it would get really hard again. I'm afraid that when I try to roll it out to put on the cake that it will cool to much before I place it on the cake and break. I am worrying needlessly or should I start over with a new batch. I have to have the cake all finished by Thursday evening because I'm leaving town to go to the contest site straight from work on Friday. Please let me know what you think I should do. 
Elaine
Maybe try massaging some Crisco into it... I'd try that first to see if it'd help.
There is another recipe for MMF that calls for 1/4 cupo f shortening in the MMF as you are making it. I started doing that and it make a big difference in softness. But since it is already made I would knead some in like ntertayneme said.
Good luck at your contest!!
The recipe I use calls for 1/2 cup of crisco, 1 pound of marshmallows (you can use the big or mini marshmallows), 2-6 Tablespoons of water depending on how dry your house is. ( I swear my kitchen is a moisture sucker LOL) and 2 pounds of powdered sugar. I love this recipe. The only time it didn't come out is when I tried to add americolor to the melted marshmallows. It totally changed the texture. I tried it twice and both times I tried I had to throw it away. I have added wilton to the melted marshmallows with no ill effects though. All that said, I agree with the other advice, add more crisco, and a little bit of water (just get your hands wet) and then knead.
http://www.cakecentral.com/cake_recipe-3113-Lisas-Best-MMF-Ever.html
This one works well mom2ty .. the added Crisco adds elasticity to the MMF and helps with the drying/cracking some get when working with it .. HTH 
Thanks everybody! Cakecre8tor, that sounds like the recipe I used, but I thought the 1/4 cup shortening was just to be to be kneaded in. I will try to add more tonight and see what happens. The first and only other time I made MMF I used the recipe on CC and it turned out perfect. Maybe this bag of sugar was more than 2lbs. I was afraid that I had overheated the marshmallows. I put in microwave for 3 minutes then when I added to my powdered sugar it was all crumbly then I melted a few mini marshmallows with another Tblsp of water and added in. The mixture was still very crumbly at this stage and I dumped it out on my Crisco covered counter and kneaded until it all stuck together but it still wasn't as smooth as the first batch I had made. If I ever get this cake together for the contest I will post pictures when I get back and let you know the outcome. Thanks again for all your help!!!
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