David Lawrence McKay came in to the office this morning and Davis Bitton was in on the conversation. He wanted to discuss the preparation of a biography for [his father] President David O. McKay. ... I told him if he wished to do it that way [do it privately through the Mormon History Trust Fund] that :
... The family would have to get approval from the First Presidency and the History Department for us to have access to the papers and if any papers are still with the family we would need to have access to those.
3. The family would have to agree to the preparation of an "honest" biography-well rounded, relatively intimate showing the warts as well as the positive side of President McKay.
Brother McKay said he would talk this over with the family and get back with us. ...
He talked as though all the McKay papers including diaries and scrapbooks are upstairs in the History Department. [Former secretary] Claire Middlemiss has copies of the diary-which is really her diary-but the original is upstairs. Brother McKay said he has access to the McKay papers and he might designate us as his agents in having access to them. ...
[Confessions of a Mormon historian : the diaries of Leonard J. Arrington, 1971-1997, Gary James Bergera, editor, Signature Books, 2018]