I've had no problem covering cakes with fondant, but today I'm trying to cover a cake dummy in fondant with no success. The fondant keeps breaking off right around the edges so I suspect it is probably because I haven't sanded the edges down enough. Or it could be the fondant, I'm not sure. I typically use satin ice for my cakes, but i'm using wilton for the dummy. 

The cake is for a cake show (my first ever entry) and I really want the edges to be sharp so I'm reluctant to sand them down more. 

 Do I have to choose between sharp edges and smooth fondant?

AHi. I've covered my cake dummies with cake boss's MMF with no problem. The recipe is on her website. I also use Veena's Asmanov's MMF recipe for everything. It's so flexible and I can roll out it very thin. When working with any of them I use glycerine instead of shortening. HTH

I just tried it again, sanding the edges down even more. I'm going to say it's the fondant. Not as bad with ripping but still a mess nonetheless. I'm going shopping for satin ice, if I can't find it--I'm going to stick to what I know and ice the dummies with buttercream.  I  should forget the entry altogether. I know I'm not gong to win, it was supposed to be for fun, but this is seriously got me stressed and is not fun anymore. 

AI've read on here that Michelle Fosters recipe ( MFF) is very easy to work with. I personally have never made or used it but I've read that its very flexible and easy to work with. I have read that if you make fondant that you need to let it sit overnight before using it. I agree that caking can be very stressful especially if you are a perfectionist. Hope whatever fondant you use things work out for you. Try to relax and keep it fun.