It seems quite common in some cultures, like some Asian immigrant cultures here, to have “family friends” – where the whole family knows the whole of the other family and visit each other as a family, in a similar way to close extended family. Like the parents are friends and then the children also spend a lot of time together. In some cases the kids stay friends or at least acquaintances when they become adults, in other cases not as much.
This can let parents socialise without having to find childcare and gives kids more social interactions while growing up, especially when they’ve left their extended family behind in another country.
IME I haven’t seen this amongst non-immigrants in the UK as much. Is this a common thing in your country?