I have visited Haddo House & had a lovely visit with June, Marchioness of Aberdeen & Temair. the owner. She was a close friend (actually a distant cousin) of a relative of mine.
A very down to earth lady, who was out in her garden working when we arrived. She has turned Haddo in a thriving Arts Centre, including the Haddo House Choral Society, an annual Opera production, choral concerts, a bi-annual Shakespeare production, etc. Her son has, I believe, taken over the operation of this part of the estate & there is a trust that administers it now.
The booklet is very interesting & informative. I'm sure you could obtain it on-line through the National Trust. I too am in Canada.