In Fable III you have two options for changing the marital home:
- Hold your spouse's hand and walk or fast travel to the new home. Press 'A' to interact with the property sign and select Set as Family Home.
- Interact with the map table in the Sanctuary and zoom into the region your family is in. Hover over your current marital home and pull LT. You should see an image of your spouse and children, if applicable, floating over the map. From there just go to the desired home and with your family hovering over it, pull LT again to move them in.