Correct me if I'm wrong, but what you're describing is client-hosted Bedrock servers, not a persistent, always available, self-hosted server. AFAIK connecting to a friend's world in Bedrock is free, but they must also be online. Hosting a persistent Bedrock server is a paid feature (Realms).
Additionally, highlighting that Bedrock Minecraft is not supported on Mac.
There are surely other ways of enabling multiplayer Minecraft for a family than what I've described, but this is the way I'd recommend.