> * Simple for family members to download and use?
> * Opensource (server & client)
Can install your own prosody instance or use one of the many free xmpp servers avalable.
> * Available on Linux, Windows, iOS and Android
I don't know about iOS, but on Android Conversations is excellent: https://f-droid.org/packages/eu.siacs.conversations/ and https://play.google.com/store/apps/details?id=eu.siacs.conve...