Hello, thanks so much for the previous post about HKG travel tips. I have another question regarding flexible ticketing. My sister is expecting a baby and currently lives in NYC. I reside in Chicago. I travel often between NYC/PHL and CHI airports, but all of these tickets have been on fixed dates. The baby's due date is 7/10, but the baby could "pop out" anytime a week before or after.

Because I have no clue when the baby will "pop out", is it possible to book a ticket with flexible dates from 7/3 through 7/17? I'm sure this has a premium, but what is the procedure in booking this type of ticket online if available? Thanks in advance.