If I had not met the red-haired boy whose father (1)
Family matters are already being introduced. We're not to the speaker's family yet, but it's important nonetheless.
as he was dying had not had an elder brother (6)
Merwin is weaving all the family ties together, even if it's a family far removed from the speaker's.
leaving two children one of them with bad health (8)
Again, Merwin is showing the interconnectedness of families and how they continue on through the generations.