The WTS started pushing articles on the dangers of large gatherings. I can't find them but remember some articles from the 1980s going in depth into the reponsibility of the person organising the party, even if a sin is committed elsewhere after the party had finished. That scared my father about having large gatherings at our house.
Here are some articles discussing large gatherings.
*** km 7/74 p. 3 Social Gatherings ***
Occasionally we hear that brothers or sisters have rented facilities for dancing, skating and other socializing by Witnesses. The Society has received a number of letters from brothers who are disturbed over what they observe or hear is taking place. Are such arrangements proper?
It is not the business of the Society or the elders in the congregations to make rulings as to what individuals may or may not do in arranging social gatherings, although loving counsel by the elders is certainly appropriate.
It definitely is proper for Christians to be hospitable. (Rom. 12:13) But when arranging to entertain others, the size of the gathering is a factor to consider. Experience has shown that there can be pitfalls and problems in connection with large social gatherings. The one who is the host has a serious responsibility. He is accountable for what takes place at a gathering that is under his jurisdiction. At a get-together in one’s own home it is not usually difficult to determine who will be present and what the activities will be. But problems along these lines may increase when there is a large group in a rented facility.
*** g86 11/8 p. 12 How Can I Have a Good Time? ***
Keep your gatherings small and avoid difficulties.
*** w87 11/1 p. 18 Are You Remaining Clean in Every Respect? ***
From South Africa comes this report: "Another danger that threatens the moral uprightness of many is large parties . . . some of which were held after sessions of the district convention." However, smaller Christian gatherings that are well supervised seldom deteriorate into "revelries." (Galatians 5:21) If alcoholic beverages are to be served, do so under supervision and in moderation. "Wine is a ridiculer," and under its influence, some brothers have dropped their moral guard or awakened slumbering weaknesses. (Proverbs 20:1) Thus, two young ministers engaged in homosexual acts after overindulging in alcohol.
*** w92 8/15 pp. 16-17 Social Entertainment—Enjoy the Benefits, Avoid the Snares ***
Yes, while not condemning appropriate entertainment, the Bible offers us cautions. These include counsel to keep social entertainment in its place as to time and quantity. It also warns us about pitfalls that have been all too common with large social gatherings.—2 Timothy 3:4