Specifically, I need one that will allow me to combine households at the neighborhood screen. All of the larger household cheats I've seen will let couples keep having babies once they've hit the maxis-defined capacity, or allows more than 8 sims to be made at the CAS screen, but I haven't seen anything that allows this and I urgently need to know if this thing exists. Thank you for your help in advance.

You can't. You have to use some sort of teleporter to add the households together.

You can with the cheat, though, (uintProp maxTotalSims and so on), I know I added several bin households (some numerous like the Newsons) to one lot in order to townify then delete them, I did the same in uni with all the bin families, and I don't have a hack for that.

http://modthesims.info/d/250640

As for moving in from hood view you need this in your userstartup file.

uintProp maxTotalSims 50
uintProp maxTotalHumans 35
uintProp maxTotalPets 15

You can change the numbers to what ever you want to but make sure the bottom 2 = the top one.