All you need. Nothing you don't.
Here’s a scenario which might appear strange to us but not to those who lived in the earliest days of the church:
A guy my age, as a father, grandfather, and yes, as a great-grandfather might have several dozen of his own kin coming over for a regular meal and a meeting in Jesus name. That’s not to mention all the in-laws of each married child from the other side of their families. Several dozen would certainly qualify as real church according to anyone with whom I’m acquainted including my own relatives which disapprove of house church.
Young teens married then and lost no time in bearing children. There was no birth control being practiced as a rule and the lights went out early.
Yes, it would have been quite possible to host a “family church” in which the teeming crowd overwhelmed the house. We can’t assume that all the family members would have become Christians, nevertheless the numbers could have been surprisingly high.
In round figures, Carolynn and I might have married and had the first of our 6 children at age 15, who each had 6 kids by the time we were 40-something… you get the idea and can have fun with the math. That’s a big bunch, no? It must also be mentioned that the average age of a male in the Roman empire was only 40-something at death. So I’ve been told. Wars, disease, and persecutions took their toll.
I don’t get the idea that “family church” was the norm then but I believe it is perfectly acceptable and not to be apologized for. I do believe that we should invite others, too, whenever possible. Each person brings something. Why would we not welcome them into our fellowship or hesitate to join theirs? If we are practicing hospitality we surely would. That said, I do believe that the meetings were to be intentional and regular but that wouldn’t exclude spontaneous ones. What is ‘regular’ may vary, I freely acknowledge. That’s a topic for another day. I just wanted us to consider the domestic situation of some of the large Christian families in the ancient world. The Bible, btw, mentions several household baptisms. There are also major implications here for the Lord’s Supper and eldership, too.