It seems pretty clear that Connie didn't live anywhere near Michael until after the death of their mother, when she humbly asked to stay close to home and take care of him. Another clue of that is at the beginning of the film, when mama mentions sending a car to the airport a week earlier from wherever Connie (and Merle) was supposed to be coming from at the time.

I also never got the impression that Fredo and his wife Deanna had ever lived at the Tahoe estate. Having been in Vegas for several years before Michael relocated to Nevada, it's possible he already had a decent place to live and there would be no need to move him to the lake

Util of course, it was time to put a bullet in his head.

Apple