It says right at the begining if Appendix C that 'The names given in these trees are only a selection from many' in other words not all descendants are recorded.
Remember these trees come from the Red Book kept by Elanor and her descendants. This of course is why Sam's children are fully listed. Note also that *all* the other trees end with the generation of the WR with the sole exception of Faramir son of Peregrin, who just happens to be married to Goldilocks Gamgee!
It is probable that Pippin and Diamond had several other children, but they didn't marry a Gamgee and so are not named. And none of Merry's brood married into Sam's family so none of them rated a mention in the Red Book.
|