Blaise If this was a laughing matter, I would have asked whether it was the "Friends with children" or the "Friends this would be relevant for" part that disturbs you, however, I will refrain from making that joke.
I can see how it can be disturbing, as it does potentially imply something that is huge and life changing even to those who knows why they are included.
Seeing as how you can see the message, or more importantly: seeing as how you're expressing interest in this: Of course you're welcome to show, and I'm sure Adrian would enjoy your company there as well. Buying presents for six year olds can be hard enough, even more so when you don't know them, so keep it simple (if you want to bring a present, that is). Isla loves Quidditch (Puddlemere in particular) and Liam is a musician through and through. Aside from that, I'm sure that they would love to meet a friend of Adrian's.
As for where you should begin (whether you should begin, I'll leave entirely up to you); through the Foundation I have worked with a private investigator in family matters. He's very discreet and very good at his work. If you're interested, I'd recommend him to get your search started.