I don't know where to put this, so I hope it's in the right place!
One of my *things,* that doesn't seem to necessarily bother anyone else, is a fairly rabid stance on seat belts. I do not like anyone in my car riding without one - my BIL stormed out of my car and threatened to walk home from a restaurant a year or two ago because I insisted.
Last night, after dinner, DH was driving home. I offered MIL the front seat, but she declined and chose to sit in the back. I turned and saw she was not wearing her seat belt. I asked if we needed to adjust the car seats so she could buckle up. (For the record, there is access to the seatbelt the way they are now; I just was trying not to make a thing.) She said no. I said "oh, let me switch and sit in the back then," to which she responded, "No. I'm fine." It was getting late and we were still long way from home, so I let it go, but I don't want to drive all the way to vacation and back that way - MIL is come with is to Maryland for a week at the end of the summer.

Can you help me draft a diplomatic email to her? Here is what I have:
I'm so glad that you are coming with us on our Ocean City vacation! We all love it there so much, and the kids will be so happy to spend time with you. There is one issue, however, I feel we need to resolve before we set out; I feel strongly that people riding in our car, regardless of age or seat position, be buckled up safely.
New Jersey and Delaware have seat belt laws for every passenger, even those in the back seat, and Maryland will have one going into effect this fall. Not only is safer for the individual to wear a seatbelt, but in the event of an accident, you run the risk of becoming a projectile and injuring others in the car.
DS and DD love you and look up to you, and it is important to me that as a role model you have a seatbelt on as well.
I am happy to offer you the front seat if you would be more comfortable up there. I do know that the back is somewhat crowded with both carseats; poor DS will likely be rear-facing until he is 6 years old, since rear facing is 5 times safer,8
and we bought a car seat with the highest possible rear-facing weight limit!
Thank you, Me
-----
What do you think? This is stressing me out. (I'll obviously change DS, DD, and Me to our actual names...)
Re: MIL troubles
I agree with this. Also, I'd take out the last sentence about rear-facing before your husband sends it (or calls her to tell her the same - which sounds infinitely less hostile to me than an email). The rear-facing sentence (though I entirely agree and intend to do the same) seems unnecessarily holier-than-thou.
I'd have your H say something to her.
DH is really, really not confrontational - especially with his family. He prefers to "stay out of it." This leads to me just keeping my mouth shut rather than having a disagreement all the time over minor things, but this is really something I feel strongly about. If DH won't talk to her, I'll have to - I'm just trying to find the most tactful way.
I won't mention RFing; my reasoning was to highlight that I have lots of car safety rules, not just with her, but I can see where it comes off wrong.
The Mob Boss
Birth: 10lbs 11oz, 21.5 inches <> 1 mo: 14lbs 7oz, 23.5 inches2mo: 18lbs 15oz, 25.5 inches <> 4mo: 26lbs 8oz, 27.5 inches6mo: 29lbs 8oz, 30 inches <> 9mo: 32lbs, 32 inches12 mo: 37lbs, 34.5 inches <> 15 mo: 38lbs 6 oz, 36 inches. 20.5 inch noggin18 mo: 43lbs, 37.75 inches 21 inch head2yr: 47 lbs, 42 inches. 21.5 inch head. Woah.
NJ:
https://www.nj.gov/oag/hts/seatbelts.html
DE:
https://ohs.delaware.gov/seatbelts
I honestly wouldn't send a long drawn out email. I would either just let it be, and then just insist that you aren't moving until she puts on her seat belt when the time comes, or make her sit up front the whole way. Your car, your rules. If it really need to be addressed before the trip, then have your husband call and make it short and sweet. Like, "we were kinda bothered the other day when you didn't wear your seat belt, but it is something we will insist on on the trip, just so you know."
I believe it says all passengers.
From the Delaware website: "Everyone in the vehicle, including backseat passengers and children, must wear seat belts properly."
And New Jersey:
" On January 18, 2010, legislation was signed into law requiring all occupants to buckle up, regardless of their seating position in a vehicle. A secondary offense, the new law allows police to issue summonses to unbuckled back seat occupants, 18 years of age and older, when the vehicle they are riding in is stopped for another violation. The law is effective immediately."
My main concern is not the law, as I insist on seatbelts in NY as well, but it IS illegal in those states.
The new laws are for everyone. (See links above if you must.)
I do not want to come off as self-righteous which is why I posted on here for advice. This is something I care about, and I will not "butt out" as it concerns me and my children. I was not asking for your views on seatbelts, and how you handle things in your car or your own family, but rather how best to approach this given MY priorities. Obviously, if you don't share those values, you don't have advice to give, and that's fine. Your car, your rules.
From my reading of the Delaware website, it says EVERYONE so we will disagree on that.
BFP #2 5/27/12. EDD 2/1/13. m/c and D&C 6/21/12.
If you want her to wear her seatlbelt say rules in your car are everyone must wear a seatbelt. The end.
If you want to send her an email about it and pussyfoot around then leave it be-because its passive and she will dismiss it.
In MIL's car or someone else's car, I'd say butt out. In your own car, you get to make the rules.
I have never had people resist too much when I tell them my buckle up rule.
First we had eachother.5.27.11
Then we had you.6.16.12
Now we have everything.
And when my children are older and they follow Grandma's example and get into other people's cars and don't wear seatbelts and THEY go flying out, she'll just learn her lesson then, right?
Stop being ridiculous and just tell her what you want her to do. Seriously if you approach issues with your MIL in this way on a regular basis she isn't going to ever give a shit what you say.
Please help me make my message less ridiculous and over the top. THAT was my original question. In the event that DH chooses not to talk to her about it and I have to, what is the most tactful approach? I thought the email was less confrontational, but you all have said that's not the case - so I will discuss it with her directly. There is no need to argue with me about the validity of my rules and my interpretation of the law; they are MY rules, and not what I was requesting opinions about.
The constructive feedback so far has been to ask DH to deal with it, or, failing that, talk to her rather than send an email - any other advice?
But you know what? I *am* dramatic about my children's safety. Which is okay with me. And frankly, I would hope my MIL would be concerned with it as well.
I also secure luggage in my car, but a luggage's health insurance company has never sued anyone so that's not as big of a concern to me. In my car, all are belted. Adults or no.