My father was Robert Platt Nelson. I do not know who Eldon Platt was. Is the Earl that you are referring to Earl Newcomb? I only know the information that I sent you. It came from the Newcomb family Bible that originally was Platt and Sarah Jaquish Newcomb's. Grandmother (Lessie Angelina Newcomb Nelson) had continued making entries in it after it was given to her.
My parents had contact with Earl's children, but I never met them and have no way of contacting them. I don't recall seeing any of their names in my mom's old address book. I will try to find it and double check. No promises on any success there. I will also dig out the Newcomb Bible and check on the data there.
My direct e-mail address is firstname.lastname@example.org
Have a great day. Todd Nelson