"In the early 1980s I spoke to the Rav about how the Lubavitcher Rebbe zt”l viewed adoptions. The Rebbe generally opposed adoption within his community because he considered the Issur Yichud DeOraita (prohibition for Jews of opposite gender to be in seclusion) to be applicable in the relationship between an adoptive mother and her adopted son of bar mitzvah age. He considered the Issur Yichud DeRabbanan to be applicable between an adoptive father and his adopted daughter above age twelve. I know from many prior conversations with him that the Rav differed on this matter and considered the functional parent child relationship to be sufficient to eliminate the Issur Yichud, despite the absence of biological relationship
As we spoke further of this debate, the Rav asked me, “What do you think the Rebbe does when there is a family in his community whom he himself thinks ought to adopt children?” I had no answer. The Rav broke into a broad smile and said. ‘Then he sends them to me to paskehn the she’elah!” What an extraordinary picture the Rav provided us with, of two giants, understanding that their opposite positions were both Divrei Elokim Chayim [the words of the living God], who were able to use the position they personally rejected to serve the emotional needs of people for whom they cared as a shepherd care for his flock.
Thus the Rav not only understood well the existence of legitimate diversity in halachic decision making, but was committed to upholding the responsibility of decision making being based in the local rabbi, not in some central institution or person. Even when he personally did not agree, he understood that the decision should be made by the shepherd who loved and cared for his flock."
Source: Master of Generations: Reflections on Reflections on Rabbi Joseph B soloveitchik Pg 63