The small group that I am a part of meets your definition of a House Church. We are small, rotate our assembling from one member's house to another, we vary in number at each gathering from 5-12, depending primarily on work schedules, or other responsibilities that might prohibit them from attending. For this reason we have chosen to meet twice weekly, Tuesday and Friday, so that everyone has an opportunity to assemble with others at least once each week.
Four of our members attend, on occasion, a local Apostolic Penteostal church (non-UPCI), as I do also for some special event. One of our members, a former licensed member of the ALJC, was even invited to preach, & accepted, on at least two occasions that I am aware of, to do just that. The Pastor of that assembly was invited, and in fact, did attend one of our gathering where the topic of discussion was focused upon our Lord's commandment of
Matthew 6:33. I was later told that they even used much of what we talked about in a sermon afterwards at that assembly.
Each member of our group has been baptized "in the name" of the Lord Jesus Christ and have received the baptism of the Holy Ghost, that is, with the exception of a young couple that have recently started attending. The husband was raised by his Grandmother in a Trinitarian Pentecostal church, and his wife was raised by parents who were Jehovah Witnesses. They both seem to be very attentive to our discussions and join in with many questions concerning things which differ from what they have been taught.
Our focus from the beginning was to seek out as many "un-churched" Oneness Apostolic Pentecostals as possible, and offer to them a non-institutionalized setting wherein they might find comfort and fellowship with "like-minded" people who have, because of their individual reasons, become separate from the institutionalized Apostolic Pentecostal churches, yet desire fellowship with others whose core beliefs are the same. We are slowly achieving that objective, and have set the limit at 15 people before dividing to begin a separate House Church group.
This is because we are an "ever-member participating" group, where each person is allowed to free expressly their views on a matter. Although I, as the eldest, have been "elected" as the Teacher and the one who exercises control over the activities, that is, insure that only one speaks at a time, but encourage everyone to participate in the discussions, I am not, do i want any to consider me as a Pastor.
I was greatly encouraged when a young man, who is also an un-churched Apostolic and had learned about our group, called me and asked if he could begin attending. He is a student at a local colledge & desired to know when we met, so that he could arrange his winter classes so that he could be free to attend. So we are growing, and that is great news!