All observations are automatically “added” to each place that they fall within. That is, if I use the observation page to search for a place, the observations that were made within that boundary will show up in the search.
For example, for this observation: https://www.inaturalist.org/observations/28838354
I do not have to manually add it to (and in fact there is no way to) Cook County, or Illinois, or the US. It will show up in the search for those places, e.g. my observations in Cook County on that day:
https://www.inaturalist.org/observations?on=2019-07-14&place_id=1859&user_id=bouteloua
A bit more about these “Standard Places” vs. “Community-curated Places” here: https://www.inaturalist.org/pages/inat+standard+places
There is one major caveat, explained in more detail in the FAQ, which will apply to some of your geoprivacy = obscured observations: https://www.inaturalist.org/pages/help#placeindex
And so, there is really no need to change the place descriptionif your main concern is falling within the correct place.
Regarding the private property, since it sounds like they want to maintain some privacy, I would probably not create a place on iNaturalist unless they requested one.
If you are able to share some map locations publicly but do not want to encourage people to visit the location, you can use the description section to note that it was private property, but it’s common sense that people should check accessibility first. I don’t think people tend to look at the locality notes (the section by the GPS which you were changing manually. See this similar conversation for a few alternative takes on sensitive locations: https://forum.inaturalist.org/t/off-trail-observations/1621
You should be able to type directly into that parent field and pull up any place in the system.
