I made a batch of MMF today and I already know it's going to be too dry. I tried adding just a tiny bit of water, but it is still cracking when I knead it. I greased the table surface with Crisco but it still just feels weird. Can I mix this bad batch in with a better batch or should I just throw it out?

Knead in some Crisco and see if that helps it.

Don't mix it with a good batch. If crisco makes it too soft to cover a cake, toss it in the freezer and use it to cover cake boards...looks beautiful and it doesn't matter if it's soft or sticky. I always use up my old fondant that way

I wouldn't mix it with a new batch either. Sometimes I put it in the microwave for a few seconds. It helps with pliability. But be CAREFUL, you can get burned badly from it. Hope this helps.

I've done this before too and one time got so frustrated with adding tiny bits of water and it just getting worse that I thought "F$%$ it! It's dry so I KNOW it needs moisture!" and I poured more so much water in it (just experimenting at that point) that it got all gooey, milky and messy and squeezed out between my fingers.

Guess what?

It brought my fondant back. So, since then anytime I get a too dry batch I just pour a bunch of water in - not tiny amounts. Knead it like crazy. It'll get all gooey and worse and you'll think you ruined it but keep kneading and adding then let it rest again over night and it'll likely come back.

It's a "bad batch" so experiment with it. You'd be surprised how resilient that stuff is.