Best diaper bag for a Phil and Ted stroller for 2 kiddos -- xpost in strollers

[hillview]

I currently have a Skip Hop Duo and it gets the job done for just DS. We are expecting a second baby in August and going to Rome in November. We will get the P&T Sport when #2 arrives. #2 will be in the infant mode in the P&T and am looking for a large diaperbag for the 2 kiddos when we are out for the day in Rome. Any suggestions?
TIA!
/hillary