So I decided to start a rotational save file where I play all the families in Henford on Bagley. I have therefore moved the NPCs onto lots in Henford on Bagley. The mayor and her son are now living...
They are in the hidden household section of the game. You can bring them out with the MCCC mod, or befriend them to be able to ask them to move in. The Crumplebottoms are not sisters.