Well, I found the answer to one of my own questions.... wow, the things I overlook!!
(Per the MA FBI Bulletin). She was born Joan Carolyn Bard, and adopted by the Nattrass family.
Also, Joan's aunt, Florence Bard, visited the Risch's just a few days before her disappearance.
But, look at these news reports:
The Brooklyn Daily Eagle (May 13, 1932) mentions both Frank Nattrass AS WELL AS Joan and her mother (two separate items, same paper, same date)
Mr & Mrs Frank E Nattrass of New Rochelle NY and formerly of Brooklyn have taken up a permanent residence at the Standish Arms.
Mrs Harold S Bard and her daughter, Joan Carolyn Bard, of Winnetka Ill and formerly of Brooklyn, have terminated their visit with Mrs Bard's parents Mr & Mrs James B Aimer and have returned to their home in Winnetka.
https://www.newspapers.com/newspage/59984461/
And, another mention of Joan and her parents (April 23, 1932):
Mr. and Mrs. Harold S. Bard and their daughter, Joan Carolyn Bard of Winnetka, formerly of Brooklyn, are visiting Mrs. Bard's parents, Mr. and Mrs. James B. Aimer, 2610 Glenwood Road.
AND, the fire is reported here, Brooklyn Daily Eagle, Feb 25, 1939:
"H.S.Bard and Wife Suffocate in Fire Former Boro Couple Trapped in N. J. Home Funeral Here Monday A double funeral service will be held at 2 p.m. Monday In the Fair-child Chapel, 86 Lefferts Place, for Mr. and Mrs. Harold S. Bard, former well-known residents here, who were suffocated Thursday In a fire in their home in Midvale Road, Mountain Lakes, N. J. Mr. Bard had lived here for 30 years and was an active member of the Bible Class of St. Mark's M. E. Church. Mrs. Bard, who was the former Josephine Aimer, was a member of the same church. The couple were married there 15 years ago. Mr. Bard formerly was asso American Diplomat"
http://bklyn.newspapers.com/newspage/52772631/
In the link below, is the engagement announcement Alice Aimer (Joan's aunt) to marry Frank E Nattrass.
http://bklyn.newspapers.com/newspage/57564384/