I don't understand how those in a pool don't DEMAND to see a copy of all tickets bought BEFORE the drawing. I've never been in a Mega Millions pool, but I do play a lot of NFL type pools, and you ALWAYS have what everyone played BEFORE the games are played!
But if this winning ticket was bought on a single ticket, why couldn't she have bought the winning ticket on her own? If she's buying tickets for the pool, she's buying them 5-10 at a time.