How to identify housemates in a mobile application?

Question

Mobile development

We are making a simple mobile application for our residential complex (House) .

It is necessary that authorized users of this application be only real people - residents of our house .

What ideas are there in terms of identification (validation) specifically with reference to the house and apartment?

Initially, there was an idea to cooperate with our Management Company - but it did not go to a meeting.
They also offered to send photos of the upper part of the Apartment Acceptance Acts - but there is personal data - many do not agree to do this for the sake of registering in the application.

Naturally, the authentication itself will be, as usual, via SMS to the phone, but how can a person further confirm that he is valid from the 13th apartment of our house?

Answer 1

Print out unique codes - for example, QR codes, or pin codes, and scatter them in the mailboxes of apartments.
Use them in the application to connect real residents.

Answer 2

At the entrance you publish an announcement that the application has been published + there is an access code in the same place.
There will most likely be 200-300 apartments in the house, there will be 2-3 crooks from the strength of a person (yes, I believe in people -).
Come visit problem apartments and personally find out the phone number. Surely there is a council at home, they can do it.

Answer 3

Go around the apartments with your feet. Those who don't need it won't use it anyway. By the way - what about tenants? Here is a person renting a hut in the house, the owner lives the hell where ...