http://www.tyett.com/images/panelbox.jpg ..you mean like this?
For a 3-family, you *may* need a 4th meter - for the house/common power. Check with your AHJ about this, some areas have this requirement - some don't.
What you "want", may not be what's "required". In NJ, a substantial renovation like the one you describe (re-zoning, over 50%, etc) might trigger a complete renovation requirement.
[This message has been edited by Celtic (edited 01-13-2006).]