- Whether family or friends, always suggest it as a "fallback" for when "preferred service" is down and to use when discussion ultra-sensitive topics or sharing financial files. With time they may just stay connected to it if the friction to do so is low. It has to be their choice, not yours.

- What helps? Add more incentives such as perks that "preferred service" does not offer. No file size limits. No or few file type limits. No content filters. Add emoji's or gifs that align with their inside jokes and their style of humor. Keeping random people away. Making them administrators or moderators and let them decide how it operates. Do not moderate or power-trip over your friends or family or they will leave. Database and file backups become even more important but they will feel in control of a thing. Have a keyword or code word they all learn means to go check the private platform that "primary platform" would not recognize. Maybe when they see "Turtle Farts!" they know to go log into your service.

- They may just stay on their primary preferred service. Every group is different and not every group will see the benefits of your fallback service. They may not appreciate the work you put into setting it up for them.

Curious if you've tried Snikket, and what hurdles you ran into (if you did). I made it with the primary purpose of moving my family communication over to XMPP, and I succeeded with that (improving a bunch of stuff in the process). I'm not claiming it's perfect (a known weak point is the iOS app, but we're actively working on solving that...)

Improbable. This technology does not have a stable client and is overrun by garbage.

Try vibe coding your own app that your family and friends would install, and have this as the background communication layer.

Good luck!