What do you mean by that? Could you elaborate?

I think that he means that once you've put lots into place and added the first families into the neighborhood, do you ever move in more families, or do you limit yourself to those families and their offspring?

With my little 'hood of Cedar Hollow, I would occasionally move in another family, but I mostly tried to make something of the families I moved in without much thought when I was just trying to populate the hood for my "main" family. (I don't play rotation-style; usually, I focus on one family for as long as I want, and I play with aging off.)

I think it started about two years ago when I started using pre-decorated but empty neighborhoods. I was searching through plasticbox's lots when I found their children's home. I decided to try it because I was so bored of my perfect family rut, and it turned out to be amazing! I love watching them grow up while trying to balance 7 kids with one adult. Since it's an orphanage none of the kids are related so it's always great to see ACR take over when they get older. Eventually they all grow up, find love, have kids, etc. while the lady who owned the orphanage usually finds something else to do, but she still regularly visits her "children."

Mostly I play the game as it comes, playing all the sims provided; but while I was playing Strangetown, I began to wonder where all those aliens were coming from. I decided they were coming from Mars.

I never use the shopping district supplied, because I don't like the houses or the sims; so I set up a new 'shopping district' called Mars, using a dirt version of the Strangetown template, and built 'The Lookout' on top of Curious hill. I created two green-skinned pioneers to live there, and now there are five. Then I built 'The Landing', an extremely old building on the edge of the Beaker crater, and look forward to creating two or three more Martians.

I fear this alien menace may well swamp Strangetown, and drive out the Grunts, the Curious and the Beakers. If everything gets out of control, it may be time for a rain of fire.

new; from Create-A-Sim/Create-A-Family?
most households in my neighborhoods have been created near the neighborhood's beginning.

"new"; sims that have done "Find Own Place"?
there were few sims that done it in past times playing; mainly ones that have became Adult.

new; from occupied lots?
like I told in beginning of this post, most households are added near the neighborhood's beginning.

You know to never install occupied lots I hope. Unless you mean the two that come with the game.

first cleared all connections with other households. afterward they were in lot bin.

Even that's not safe.

have not yet gotten Open For Business or Bon Voyage.

edit:: have been thorough in removing household connections.

No new families. None whatsoever. I don't even want all of the sims that are born into the game, I'm not about to create new ones. ACR does a fine job of populating my neighborhoods.

Well, there's your problem!

Anyway, I don't recall ever having a 'hood long enough to reach that point, but I certainly wouldn't be opposed to adding a family or two every couple generations.

It is a problem. I'm handing out plan b like it's candy. I have a male sim who lives alone in a flat, he's pleasure/popularity (or the other way around, I don't remember) and he's not allowed to try for baby. He got his roommate pregnant yesterday. Then I played his sister, who is knowledge/fortune and just graduated from college (where she got engaged to a dormie and felt the need to have a daughter) threw a party to which she invited old non-college friends. All of the sudden, I hear sims falling in love and I find her in a far corner of the yard, getting it on with her second cousin, on her dead grandmother's bed, in the middle of winter. There was a lullaby. I put the blame on the cousin because he's family and he already has two kids and his wife is on birth control but the moment I aborted that baby, she made a booty call to her fiance to make another one. So, yeah, no new families for this neighborhood, lol.

I'd also add new families as I seem interested, especially in my custom neighborhood that doesn't have townies, just the service sims that spawn automatically (someone could argue that I could mod some of those out, but that would be overkill).
Also, with smaller neighborhoods, sometimes it's necessary if you reach a point where you have adults with literally no one to marry.

I used to introduce new families when I got new skin or eye genetics to get those into neighborhood genetics mix. Though now I just do single sims like once every year when a friend comes over and I want them to make a new sim for my hood or something.