“edge” is one of the last poems plath wrote before her suicide. how does knowing this information affect your understanding of the poem?

You start to see in it presentiments of her suicide. The name proposes being on the edge or having slipped off it. Since the poem is about a "perfected woman," one begins to read it as the poem about Plath herself dead, perfect. You can see how unhappy that she feels when turning over this message and you can almost see what she is planning to do.  It makes you more conscious of others who may be in need of help when you least comprehend it.

the author motivation is to show the power of animal-human relationships.

you should ask "yourself is it good enough? "