I don't allow food from home unless it aligns with the food program standards so as long as the child is getting a balanced meal and snack with appropriate serving sizes then I'm fine with it. So I use the fact that I serve healthy meals to steer junk food away from my daycare. You can go that route or just focus on teaching the others that we don't always get what we want like some of the other ladies pointed out. My worry would be that then the other parents might want to start bringing their kids their own snacks and meals and then the group (or most of) will have unhealthy snacks and food. But then again, you might be able to transition away from providing meals altogether this way.
It just depends on how you feel about it and what you're ok with.