While the Proclamation on the Family was nominally written by all 15 men serving in the First Presidency and Quorum of the Twelve at the time it was issued, it seems likely that some of them were more central to the project than others. For some reason, I’ve always thought it was Elder Nelson’s baby, although I’m not exactly sure why. Maybe it’s just because divine gender roles seems to be his favorite topic.
In any case, the writers aren’t likely to tell us who was most and least involved, but I wonder if they might have revealed this information to us indirectly. It seems reasonable to assume that those who were most enamored of the project would quote from and refer to the document most often. So I went back and checked who has referred to the Proclamation the most.