As far as I can see, there's only two possible ways it can go:
Maria, at age seventy, tells her grandchildren of what life was like way back in the 1950s. The whole thing occurs as a flashback, every now and then punctuated by current Maria's commentary. (The kids also ask about the odd parallels between the story and Shakespeare's Romeo and Juliet, which Maria doesn't realize until the kids point it out.) And the whole thing ends with Maria's sad realization that she probably should have killed herself after the whole ordeal (for closure as well as greater dramatic effect), thus sending her grandchildren into a state of shock and inspiring in them a killing rampage much like "Silent Night, Deadly Night".
Or, a die-hard theater aficionado, going through his collection of vinyl albums, finds his vintage 'West Side Story' record and plays it in his apartment, and the characters come to life and perform the show in his apartment, every now and then punctuated by the theater aficionado's commentary.
"You mean what was the best picture of the year or what did they pick as the best picture of the year?" - California Suite