WCIF these

[liverbird]

WCIF replacement landlords/landladies as the ones in game are all old when you do have young landlords/ladies in real life..  thanks in advance I have all exp & fun packs

[Prudensh]

I have successfully used the *mod that dares not speak its name* to age NPCs, townies etc down. (and up) As everyone says Simblender can do everything that aformentioned unsupported mod can do, you can probably use Simblender to do this too.

[liverbird]

Ok thanks so I just take control of the landlord/lady & change there age to adult rather than elder...

[Carlwashere]

That should do it.
I did the same thing with the head witches and a couple college professors. (Making them teens) 
Avoid messing with the special npcs, just throwing that out there. 

[liverbird]

Do you mean the freetime hobby people

[Prudensh]

I don't know about the hobby people as I don't have Freetime but I think Carlwashere probably means don't mess with the specials such as the Grim Reaper,  Social Workers or Repo Men for example. Those NPCs have their own preprogrammed actions and if you interfere with them the game goes into an infinite loop and the only way out is ctrl-alt-delete....if you're lucky. 

[liverbird]

Ok thanks but its safe to alter the landlord/lady though

[Theraven]

If you're using Insim (unsupported) or SimBlender, then I think you can alter a sim without making the sim selectable. Aging them from elder to adult shouldn't be a huge problem, but you can get troubles if you make them younger than that. Some NPCs will show up weird (face gone, hair gone... that sort of things) or turn buggy if you alter them.

I don't mess around with the NPCs too much, so I don't have a clue which are safe to alter.

[liverbird]

Ok thanks for all the helps..

[Carlwashere]

Yeah, that's what I meant by special NPCs. The hobby enthusiasts are fine to mess with. I do mess around quite a bit with those sims.
I haven't had any noticeable effects by making my NPCS younger than adult, I made college professors and head witches teens (as I said earlier) and they do everything they're supposed too. And nothing more. I haven't tried any other types of NPCs, but for the record, those NPCs seem fine. If I remember right, some of my landlords are adults already.
Anyway back on topic, changing the age of the landlord/lady should be fine.