Circles of friends and contact lists

I recently received an email from one of my sister's friends who is feeling guilty about not contacting me before my sister was diagnosed with FTD and early onset Alzheimer's.

Here's a portion of her email:

I asked her to share your phone number with me but it was an odd request and she looked at me like she didn't understand. I remember talking with Barb about getting your information so we could express our concern. Anyhow, that never happened and I let it go

I think about this often and question myself as to my poor judgement on letting this slide and not pushing harder to call you.

I remembered that incident at Barb's house and felt tremendous regret that I didn't push harder to get your information.

In an early onset Alzheimer's case, it made me think about how we don't always know our loved ones closer contacts, whether they're friends or colleagues. At the beginning of Peggy's illness I didn't know most of her friends (I do now!).

Is there a non-creepy way to create contact lists for situations like what I've described? It would have been really helpful in the beginning to be able to compare notes as to what I was seeing in my sister that made no sense. Maybe others saw similar things?

It just seem like something we should think about as we get older ….