My words of wisdom:
Try not to sound like your only purpose is to preach to them

. Before high school my levels were always around 8 and sometimes up to 14mg/dl and my previous dietitian always tried to get me to meet with others. So I was kind of in the situation that these two are in. I HATED it when the people I met with preached about this and that, it just made me feel like I was just with them to be told how terrible I was at the diet.
Just try to get to know them a little bit before you offer advice. And give them advice on things that they want advice on. No point in spending hours talking about say formula if they like their formula right

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I think it's great that your going to talk with them Aaron. Have fun with them and try not to seem like the big bad guy whose out to get them for not following their diet!