How to set boundaries with in laws gently?

My MIL doesn’t seem to have the boundaries that most people naturally follow out of common sense and often does things that gross me and my partner out. I.e licking our daughters hands or feet or sucking on her food then offering it to our toddler, she also gets cold sores too. Her parents also get cold sores and are heavy smokers and often try to kiss our little one on the lips.

Prior to baby 2 coming we want to set some boundaries so their (rare) visits are less anxiety inducing. If it makes a different they are not very active in our daughters life. We’ve decided we want no kisses (at all) and no sharing or food/drink.

How do we broach this with them on a forceful (they usually try to ignore our wishes) but also not fall out with them about it?