The grape jelly and chili sauce meatballs (sweet and sour is what we call them) are great. I switch out and use marmalade or another jelly sometimes. I have also used a large jar of salsa instead of the chili sauce. The chili sauce can be confusing for some people, it is sometimes near the catsup and is in a similar bottle with "chili sauce" on it. I have added some balsamic vinegar to mine, some people might use Worcestershire sauce (I'm allergic).
What I do is make the meatballs. Sometimes the meatballs are half beef and half sausage. I line a cookie sheet with parchment paper and put the meatballs on that and put into an oven at 400F for about 15 min. I then remove them and put them in a sprayed slow cooker, then put in the sauces. I turn mine on high until it smells, and then I lower it to low and let it cook. for us it is done when the sauce is thickening.