I started to post, then I had to run. I think you need to be a little more specific. What exactly are you (not) looking forward to?
My ILs are constantly undermining my parenting choices. I heard that My baby was uncomfortable in a sling and I should put her in the stroller. My DD#1 Never tolerated a stroller, ever, she would scream as if I was beating her. I heard I didn't "potty train" her soon enough, but her male cousin who is a year older was "potty trained" around the same time. I still hear about the earrings... I should have gotten her ears pierced at birth the way they do it in their country. I used to argue, but my DH said to just agree and then do whatever we want because we see them so rarely...
We have discussed DH taking DD#1 to Lebanon by himself and leaving me here with DD#2, but I won't agree to it because I know his family and it's awfully far to be away from mommy for the first time ever.
So, from your post:
food: I say it depends... My DD#1 can't have any sweets at all, she also doesn't do well on white flour... She becomes hyperactive and has melt downs over anything, so I would lie and say she has a food allergy to certain things... OR I would let them load her up on sugar and white flour and see what happens, then when they ask, "what's wrong with her" I would answer, "this is what happens when she has too much sugar and white flour" so they would learn. I'm not sure what you're worried about, but if it's similar, you could play the food allergy card.
discipline: No one disciplines my children but me and DH, that's not up for discussion. No spanking, no yelling (unless DC is about to stick her hand in a bee hive or fire or something like that.)
TV: Providing they are not subjecting her to sex or bloody violence, I can bend on he TV issue.
toys, etc: It's only fro a month and a half, let them spoil their grandkids a little