I'd try making bland homemade pureed pasta sauce, with some honey or maple syrup, as a pp suggusted. If that doesn't fly, try comercial spagetti sauce with just sugar, no hfcs (hey, its an improvement right)
Many of those breakfast foods can be repeated for lunch (scrambled eggs are fast, pancakes in the toaster, room temp muffins, fruit, the veggies they do like leftover (extra) from dinner).
If the grandparents aren't understanding, thats ok. You know the 80/20 rule? that if you eat healthy 80 percent of the time, the other 20 will be ok? I'd focus on improving their diets at home and let them eat junk at the grandparents house. As long as they are eating the majority of their meals at home, it shouldn't make a difference. (and as they wean off sugar, they may find themselves less interested in it at the g-parents)
btw, have you seen
this blog post? I love it. (Its not my blog, I think I can post it in the new UA?) Its so true. When you stop eating sugar, things like sweet potatos and carrots and fruit and cream taste super sweet, and things with corn syrup taste disgustingly sweet. but when you start eating sugar regularly, the sweet potatoes taste less sweet, and the corn syrup tastes good. (that's my expeirience).
Maybe don't think or talk about it in terms of restricting. Who likes to be restricted. Instead, think about it as boundless fat and other good TF things. Sugar may taste good, but fatty meat and butter taste even better once your addiction is cured.
This may not work for you or your family, but honestly, if I were in your situation, I would ban sugar and processed corn from the house for a while. (Banning corn unless it looks like corn (corn meal or fresh corn) essentially means cutting out all processed foods. it is in everything, though it may not always say corn). I would throw out (if I could afford it) all products with sugar and corn syrup or else use them up and not buy more. I'd make extras of the things they like for breakfast and dinner to eat at lunch and deal with the whining til they got used to the lack of processed food (and all the benefits of good food).
