Is there any way I can kind of merge my two saves. I populated a world and I want to move there permanently. Problem is the populated version doesn't show up when they move to the new world (it's empty). I tried putting the nhd file in my save folder which works for vacation but not actual moving. I could copy them from the library but the relationships will be lost . I have nraas traveler.

Take a vacation to the new world (the one with the nhd copied over) and have your sims stay wherever for free. It can be a vacant lot, anywhere except where you eventually want them to live.
Purchase a vacation home, which may first require changing the lot type as seen from within Edit Town of the desired home to (Player) Ownable.
Have them move into the vacation home using a phone/computer.
Invoke Traveler's Change Hometown command from City Hall.
Save (as), Quit entirely to the desktop (or Origin if on 1.69), reload.

Your sims will now be permanent residents of the new world. The original one as they left it will be available to go back for a visit or to pull more sims in from by using MasterController. Relationships between sims across the two worlds will be preserved.

More details on this procedure:
http://nraas.wikispaces.com/Traveler+FAQ
(see the Switching Homeworlds section towards the end)


If your intention is to move a subset of households from one world to another and don't want the original world and the sims left behind in your game at all any longer, then consider using NRaas Porter instead.
http://nraas.wikispaces.com/Porter+FAQ

Thank you sm, it worked! I love that the relationships stay, so I can invite people over. I'll get porter too for future uses.