Tips on creating a Save file

Sul Sul simmers!

I need some help about a dilemma I have now faced TWICE and ready to jump back in and try it again I want to make sure I can avoid this situation. Both issues were related to the apartment Stonestreet apartments in Evergreen Harbor and Jasmine B suites in San Myshuno. My process is easy without any mods or cc I choose a random from the gallery and I always start in spring and move them to an empty lot, I then go to the setting and switch life span to long and weather to two weeks in span, I also choose the box to keep werewolves om Moonwood mills. Then in manage world I delete all NPC families and then go to the gallery and pick houses I think look perfect for that world and place them on whatever lot. When I get to the stone street apartment, I bulldoze the lots and again place room lots from the gallery and even all apartments on San Myshuno I do the same. However, once I am completed, I will then add NPC remakes from the gallery and add extra NPC from the gallery to make my worlds fuller and more alive. Then I will exit the game and add my mods and cc (since many of my sims are created with ww mods and skin cc) and then add them to their designated lots. Once I start to place the Stonestreet apartment will then have a X and not display the apartment as normal. Then I notice when I place my main sim in her apartment (Jasmine B apartment, which I have created from scratch) when playing the welcome wagon (only 3 sims show up) and then get stuck in the hallway (no one will knock on the door). This is extremely frustrated as this is such an intricate part to my story line since she is supposed to meet one of her neighbors via the welcome wagon. 

Can anyone please tell me how I can prevent this in the future since I have decided for the THIRD time to try it all over again (which each time took me who entire week!) I just don't want to keep wasting my time.