Are you talking about family in your home, or family across the internet?
Anyone who is within your house should be using the internal address of the server. If they are coming in from the internet, they need the external address and you have to use port forwarding on your router. You can use both, as long as each person is using the correct IP address. This applies to any server you are running from your home, people inside the home need to use the internal address of the server, people coming in via the internet need the external address.
I know that was redundantly redundant, but as a 30+ year IT veteran, you learn to be like that to make sure people get it...and even then they often don't.
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