There was a time when Qian Jingde was also a direct descendant of the main line, but as is always the case with noble families, the essential line usually only extends from the eldest son. Any subsequent offspring from the direct line then becomes the branch family.
However, Qian Jingde was indeed born as the eldest son, his relationship with the present direct line is rather close, and his position is relatively higher than that of any elder who springs from the branch families.
In addition, it is heard that there is an outstanding young Alchemist from the 'Xue' generation in Elder Qian Jingde's line. However, Qian Xue'an, constantly being abroad, has very less interaction with Qian Xuefu.