How does the playwright use foreshadowing in the play, Alison’s House?

In Alison's House, Knowles arrives in Act 1, asking about Alison and gently inquiring if there might be some of her poetry yet unpublished. His questions, on top of the move itself, stir up memories of Alison for all of the family, and the subject of a possible body of unpublished work lingers and repeats. This foreshadows the eventual discovery of the poems in Act 3. Aunt Agatha appears in Act 2 with a leather portfolio of unnamed contents, drawing heightened interest to this possibility. The Stanhopes' certainty that all of Alison's poetry has been found and published lends dramatic tension to the final discovery.