Oh sorry, one other thing if I may. I originally thought that 来た in #4 meant that the sweets (not the parents) came, but then I got confused because that interpretation seemed to make 来た a transitive verb (with object お菓子), which seemed wrong. Do we interpret it like that, or does the fact that it's ~て来た mean that only 送る needs to be transitive, and 来た, being a kind of auxiliary, has no particular transitive/intransitive nature of its own?
I hope that question makes sense!