I don't think I'm familiar with the quotation you mentioned (though I have seen similar quotations not specific to the Feast or social portion at least).
If you looked through the Feast compilation, perhaps you noticed these two quotations on the social portion already:
"Regarding changing the order of the Feast, it is clear from Shoghi Effendi's instructions that the Nineteen Day Feast programme should start with the spiritual part, and not with the social part, which includes refreshments, or breaking bread together"."
(23 January 1985 written on behalf of the Universal House of Justice to an individual believer)
"Regarding the Nineteen Day Feast: in a previous letter to the National Spiritual Assembly the Guardian had made it clear that, although not a binding ordinance, this Feast has been regarded by Bahá'u'lláh as highly desirable and meritorious. In the "Aqdas" He has specially emphasized its spiritual and devotional character, and also its social importance in the Bahá'í community as a means for bringing about closer fellowship and unity among the believers. The administrative significance of this Feast has been stated by the Guardian in view of the increasing need among the friends for better training in the principles and methods of Bahá'í Administration."
(In a letter written on behalf of Shoghi Effendi, 2 October 1935 to the National Spiritual Assembly of the United States and Canada, emphasis added)
There are some other quotations which provide concrete guidance about meetings in general (besides the many which speak about virtue):
"Let the loved ones of God, whether young or old, whether male or female, each according to his capabilities, bestir themselves and spare no efforts to acquire the various current branches of knowledge, both spiritual and secular, and of the arts. Whensoever they gather in their meetings let their conversation be confined to learned subjects and to information on the knowledge of the day.
"If they do thus, they will flood the world with the Manifest Light, and change this dusty earth into gardens of the Realm of Glory."
(`Abdu'l-Baha, Education, no. 27
, emphasis added)
"Verily, ‘Abdu'l-Bahá inhaleth the fragrance of the love of God from every meeting-place where the Word of God is uttered and proofs and arguments set forth that shed their rays across the world, and where they recount the tribulations of ‘Abdu'l-Bahá at the evil hands of those who have violated the Covenant of God.
"O handmaid of the Lord! Speak thou no word of politics; thy task concerneth the life of the soul, for this verily leadeth to man's joy in the world of God. Except to speak well of them, make thou no mention of the earth's kings, and the worldly governments thereof. Rather, confine thine utterance to spreading the blissful tidings of the Kingdom of God, and demonstrating the influence of the Word of God, and the holiness of the Cause of God. Tell thou of abiding joy and spiritual delights, and godlike qualities, and of how the Sun of Truth hath risen above the earth's horizons: tell of the blowing of the spirit of life into the body of the world."
(“Selections from the Writings of ‘Abdu'l-Bahá”, sec. 53, pp. 92-93)
From quotations above, it seems the social portion has no structural requirements (though of course helping and encouraging others would always be advocated), so if problems occurred during the social portion, I would expect that guidance on virtue would still be relevant even if not confined to the Feast, no? Can you elaborate more on the nature of the problems (without revealing individual behavior of course)?
Even though not confined to the social portion, I do see that the Feast compilation does have this quotation mentioning encouraging and inspiring one another toward love (and it also mentions some interesting items like reading beneficial essays and giving talks, though I'm not clear at what portion this would fall under):
Thou hast written " concerning the Feast. This festivity, which is held on a day of the nineteen-day month, was established by His Holiness the Báb, and the Blessed Beauty directed, confirmed and warmly encouraged the holding of it. It is, therefore, of the utmost importance. You should unquestionably see to it with the greatest care, and make its value known, so that it may become solidly established on a permanent basis. Let the beloved of God gather together and associate most lovingly and spiritually and happily with one another, conducting themselves with the greatest courtesy and self-restraint. Let them read the holy verses, as well as essays which are of benefit, and the letters of `Abdu'l-Bahá; encourage and inspire one another to love each and all; chant the prayers with serenity and joy; give eloquent talks, and praise the matchless Lord.
('Abdu'l-Bahá, from a Tablet to an individual believer, translated from the Persian)