What about something like this:
-----------------------
<mention something nice about bother's family first. Maybe something about something really neat that your neice or nephew was accomplishing or something praising like that>
I had recently come across some information that I thought might be helpful for your daughter.
You probably are aware of the current minimum standards of keeping kids in their carseats rearfacing until at least 1 year and 20 pounds, but have you heard about the recommendations to keep kids rearfacing in their carseats for as long as possible, preferably up to at least 2 years old or 30 pounds. These are pretty new recommendations so a lot of parents and doctors aren't aware of them. If you haven't heard about the information, check out this you-tube video which highlights some of the reasons to rearface in a carseat for as long as possible.
http://www.youtube.com/watch?v=psmUWg7QrC8
And also a great link explaining the reasons to rearface in a carseat past 1 year and 20 pounds:
http://www.cpsafety.com/articles/stayrearfacing.aspx
There is a lot more information out on the web so if you do an internet search on "extended rearfacing" you can read what the experts are saying.
I was really surprised by how much safer rearfacing is, so I wanted to pass this information over to you as soon as I learned about it. I really love my neice and want her to be as safe as possible while riding in the car.
<maybe end with another positive about the family or invite them over to your house for a fun activity or mention how much you are looking forward to seeing them soon>