The contact problem, and the way round it
Every reunion committee starts by trying to build a spreadsheet of phone numbers and every one of them stalls. People have moved, changed numbers, changed names, and left the social networks you were counting on.
The approach that works is the opposite. Make one sign-up link and push it everywhere at once: the class Facebook group, the family group chat, an email to whatever old list exists, and a note to the handful of people who know everybody.
Those few well-connected people do most of the work. Every class has three or four of them and every family has an aunt who has everyone's number.
Class reunions
The alumni Facebook group is usually where the list starts, but it will not reach everyone, because a meaningful share of any class is not on it.
Ask the people who joined to forward the link to anyone they still speak to. That second layer reaches the classmates who left social media years ago, which is often the group you most want back.
Expect the list to build slowly for weeks and then jump when someone popular shares it. That is normal, and it is why announcing early matters more than announcing perfectly.
Family reunions
Families have a structural advantage: the branches are known even when the numbers are not. Send the sign-up link to one person in each branch and ask them to pass it down.
That also gets round the generational split. The younger cousins share it by text, the older relatives get told by phone, and both end up on the same list without the committee doing the legwork.
For relatives who genuinely do not text, keep a short call list. Every family has one and it is less work than trying to bring everyone onto the same system. Reaching a family quickly covers a similar problem in a very different situation.
The messages worth sending
Most reunions need four or five messages spread over months: the save the date, the venue and price once booked, a payment or registration deadline, a headcount push, and the final details a few days out.
The deadline message is the one that does the work. Tickets close March 1 produces bookings in a way that a general reminder never does, because it forces a decision.
All of them come out of the same payment, so there is no reason to combine several announcements into one long message. Scheduling them in advance lets the committee write them while it has time.
What this cannot do for a reunion
It will not find people. There is no lookup, no directory and no way to trace a classmate whose number nobody has. That part is human work and always will be.
It cannot collect money either. Ticket payments still go through whatever you already use, and the text is what tells people the amount and the deadline.
And one list sends the same message to everybody, so if the committee needs its own conversation, that belongs in a normal group chat. Sending to a list of several hundred covers what changes at larger sizes.