As the amount of third-party correspondence makes evident, d'Harnoncourt received many inquiries and publishing requests in regard to her father. His expertise of Mexican and Native American art as well as his tenure at the Museum of Modern Art (MoMA) were points of interest with many scholars. While she could not always answer the inquiries, d'Harnoncourt would at the least steer scholars to more appropriate sources--from MoMA's archives to her own mother. Occasionally, correspondents would include reminiscences about her parents or photocopies of drawings by her father. Such inclusions are noted in the folder title. Particularly endearing are the two illustrated letters attached to the Sept. 12, 1995, correspondence from a curator at the Denver Art Museum. Both were written and illustrated by René d'Harnoncourt while he worked for the Indian Arts and Crafts Board at the Department of the Interior. In the letter of May 9, 1944, addressed to Frederic Douglas, Denver's curator at the time, d'Harnoncourt expresses regret at not including sufficient "Baby data" in his earlier report. He then notes that, "When Anne arrived she weighed 7 pounds and was 19" tall...[S]ince then she has grown at the rate of an inch a month (I hope she stops before she gets a mile long) and is at present a very plump healthy and happy young lady with curls on the top of her head and brownish grey eyes...Anne is quite a sociable Baby and likes company." At the end of the letter, he includes an illustration of his newly extended family, curls and all. According to the cover letter, d'Harnoncourt should have received the original letters. Photocopies, however, are all that is attached here. Another recollection is included in the letter dated May 19, 2002, from Ruther Carter Stevenson, the daughter of Amon G. Carter and the person most responsible for building the eponymous art museum her father had envisioned. She recalls the time when the senior d'Harnoncourt was in Mexico and the family's pet boa constrictor climbed up into his bed to warm itself. As suggested by these illustrated letters, d'Harnoncourt was just as inclined to sketch as he was to express his thoughts in words. Further evidence of particular note are the three sheets of drawings dated 1946. That year d'Harnoncourt was appointed Senior Counselor of Visual Art of the Preparatory Commission of UNESCO, the United Nations entity devoted to the collaborative promotion of education, science and culture. The appointment required d'Harnoncourt to spend almost three months in London. To keep his daughter, then three years old, informed of his activities, he sent an illustrated explanation of his colleagues and their duties. On another sheet, he describes what he encounters along his walk to work on the streets of London. The third is the story of his finding the young son of the building's janitor under his desk and their interesting conversation about the boy's pet mouse. On the verso, as well as more serious side, is part of a letter to his wife, in which he expresses concern over the organization and leadership of the commission.
Correspondence of d'Harnoncourt's mother, Sarah, is not extensive and primarily pertains to answering inquiries about her husband. Most of the other correspondents are d'Harnoncourt's Austrian relatives, some with titles reflecting the family's aristocratic lineage. Most well known is Nikolaus "Niki" Harnoncourt, a frequent guest conductor of the Vienna and Berlin Philharmonic Orchestras who was also one of the first musicians to perform Baroque and Classical-era music on period instruments. The folder of press clippings d'Harnoncourt kept of her cousin speaks to his international reputation. There are also several letters with another musical relative, the mezzo soprano Elizabeth von Magnus-Harnoncourt, known professionally as Elizabeth von Magnus. At the memorial service held at the Academy of Music on what would have been d'Harnoncourt's 65th birthday, her niece took part in the tribute, singing Haydn's "The Spirit's Song." Family gatherings are the primary topic of discussion in the "Rishel" folders. The amount of correspondence is minimal.