Don't know how much help I will be, but as you may already know by now, Rosa is buried in Rochester, Haskell, Texas and is on find-a-grave.
My wife, Shirley Hileman GIBSON is the 2nd ggranddaughter of P. A. Henderson through John William Henderson then thru William Luther Henderson. I too have noticed the Aunt Ann Downing listed in the 1910 census but have found no reference for her beyond that.
I had never thought that Click and Preston Jr. were one and the same because according to my information, they were born over a year apart but then again, my information is a little sketchy so they could be.
If I come across anything pertaining to this line in my research, I will contact you.
Frank Gibson - email@example.com