Manners and etiquette!!

I’m actually curious to hear from both nannies and nanny parents on how they would react to this! Usually, upon starting a new job, I make it very clear that I am very big on manners and etiquette, especially at the table, and a lot of families definitely appreciate this. Unfortunately, the current family I’m with has kids who do not practice proper etiquette at the table. So I have had to tell all of them on numerous occasions not to chew with their mouths open, not to play with their food, not to play while they’re eating, etc… and I would never expect a family to get upset at this. Usually they’re very grateful for this, but the current family that I’m with I have an odd feeling that they might not appreciate this as much, because they don’t enforce it in the household nor do I think they really care about enforcing it. The children are school age and I want to teach them at home before they go to the lunchroom and get picked on for chewing with their mouths wide open. Also growing up in the real world, it is proper manners, etiquette, and just respectful to chew with your mouth closed as I'm sure you all know. MB is a SAHM and will often intervene when I am trying to teach the children something often times saying the same thing that I am saying, it always gives me the impression that she wants to teach them something before I can teach them something. That is something in itself that I have been very annoyed with since I’ve started, but whatever!