Hi Tanya - I have done the frozen big bags of meatballs many times in the slowcooker. They turn out wonderfully. I have done them with the marina sauce, a whole jar and also put in some peppers and onions along with it. I cook it on high for 3-4 hours and they turn out great.

I would use the plain ones for the sweet and sour, and just use your regular recipe for the sweet and sour sauce with the chilisauce and grape jelly. It will melt enough to end up covering the meatballs as they let out some of their liquid, too. Can't remember if you end up warming the sauce and grape jelly ahead of time to have it be liquid, but that's what I'd do with it and then just pour it over the meatballs.

They will be great done that way - they end up being very tender compared to doing them in an oven or stovetop.

Enjoy your party -