Doing group chats with my family of 5 using Signal private messenger. The privacy guarantee is nice, but I'll admit there are lots of little issues in Signal group chats, often between iOS and Android.
Totally just curious, did you miss Slack's notion of multiple persistent channels, where you can be talking about the wedding in one channel and the reunion with the Southern California part of your clan in another (location is just illustrative)? Or is creating multiple groups, one for each part of your family okay?
We use posts as 'channels'... they're generally short-lived.
There isn't nearly as much 'chatting' there as 'information sharing'... announcing milestones (pre-public baby announcements)... Etc.
For example, we just had one family decide they want to go to Knots Berry Farm the day after the wedding... Those who are interested replied, those who won't be sticking around or otherwise not interested didn't reply... so each post becomes a sort of persistent channel about a topic.
We have posts about the suggested hotel, and another post about a large AirBnB house that several families are going in on.
We're talking about 5 comments a day, max... and sometimes weeks w/o anything. We're generally fairly 'public' about things and use regular wall posts for general communication.
I'm not sure what's "crazy" about it. My family uses a private Facebook group and it works very well. We send events and keep each other updated on our lives. It's nice because there isn't a separate login to create or app to install.