Thank you for your post.
You may want to consider having this file on the network. That way, the file is in one place, and everyone can access and update it (depending on access privileges) simultaneously. That is, no need to copy it to each person's machine. It is available at all times with the most recent information.
Is there a reason why each person needs their own copy of the file?
Sorry, my poor description reduced the effectiveness of your answer. I don't have a "network" in the sense that there is a central hard drive and storage as in a business situation, but rather I have a wireless "network" via Airport Extreme to wirelessly connect to the broadband connection.
When you update your database and are away from home as you state....are you in places you have wifi access or are you updating while completely offline?
If you have inet access away from home...I'd setup one of you home machines to serve out the database, open your firewall, and connect to that remotely.
If you are offline while away and updating, I don't see any other way then what you are doing now...
When I update the database I do have wifi .How do I do what you suggest?
lookup sharing in your filemaker help.
I would use ONE of your stationary(home) machines to share out the data (server)
then use your other computers as clients...
IWP - Instant web publishing may be the easiest route to look at. (all your client computers connect to your main data via a web browser)