The psychology of the “mother cat” glues the stray cat communities in the streets of Rome because away from the human interference cats follow the rules of belonging to a certain definition of “home and family”.
We know that cats are social creatures. When you bring home a little stray, base its interaction with the house cats on the cats’ social needs.
A cat family that is used to receive attention would expect you to offer it the same attention as you do to the little one. There are cases when the stray is adopted without reserves as there are cases when the house cats react adversely and you need to intervene.
In a family where pets are in a larger number there is definitely a problem of territory. Cats, especially males, are very decided as territory goes; so if inside one home there are more than two males the territory issue is extremely sensible.
When strays are in question the hierarchy is even stronger but if there is a particular case in question involving adopting a small kitty the things are completely changed.
In spite of the theory that cats are bad parents, the little stray would accommodate extremely fast and the “family” of home cats will adopt the little stray cat because they do not see in it a territory breach.
Take for example a mature cat that over the years gave birth to several generations of kitties. Such a cat would respond to the presence of a new kitty by smelling it, grooming it and doing its best to make the little one feel comfortable.
If along the old mother cat, there are other cats inside your house, they will adopt the same kind of attitude towards the little stray.
If you ask yourself why this happens, the answer is rather simple. The cats are matriarch communities. A mother cat, if not separated from her kitties will rule a large family of offspring and relatives just like a queen rules a dynasty.
In the case of a small stray, the “word” of the oldest female is law. The little one would do its best to introduce itself to the other members of the cat family and you will see this by its way of purring and rubbing against everything whether that everything is the other cats of yours.
In this case purring is a sign of submission rather than happiness and you will see that the home cats are seeing it as such. As a consequence the second you see the other cats letting the little one rub against them you may consider it is part of the family.