Hi Carl, since you failed to mention ways to get the single father with his child I thought I'd share some tips, as I do this with illiginamite (however you spell the word) all the time:
All you need to do for most of these instructions is edit town or Cheat codes:
-Most of the time, just change the active household. If you see a mother and her baby, simply check her family tree, and her relationships, her boyfriend/fiancee will be listed as the father, or even, check the family tree once that's done you have two options:
Simply Go to edit town. If the mother is living with more than one person (Roomies, Working Friends), and the father is living by himself, simply go to "Split up Household" and select the mother and her baby, and then click Accept. Then, you simply drag them to the father's house. If the daddy is living in a house with 4 different people (Cycl0n3 Sw0rd, Stiles McGraw) and the mother is living alone (ex.Agnes Crumplebottom, Jamie Jolina etc.) Simply do the same option as above, and drag him to his girlfriend's house with the baby)