I don’t think so. In his entry on Wikipedia no other sibling is mentioned.
LBJ life, written so far in 3 books, I believe will end with the 4th about his presidential years. Caro dedicates about 10 years of research and writing to each book and he is not young himself.
In the first book there is a fascinating chapter on the Texas Hill Country life, his description is so vivid you are totally transported in that time.
I am interested in reading about LBJ because it is part of the political history I did not know as I was raised in Europe.
I did not know there was more than one book. The one I read did go into detail about LBJ stealing the U.S. Senate election from Coke Stevenson. It also makes me think a lot less of Truman who helped Johnson get away with it after he basically was caught red handed.
Also interesting that famed Texas Ranger Frank Hamer was the one who caught Johnson, he was the same guy who caught Bonnie and Clyde.
I used to date a little cutie who went to South West Texas state. She told me that LBJ stole the senior class treasury when he was at SWTS.