Some friends and family members are traveling SFO-FCO this summer. They can each save about $300 if they book SFO-BRU-SFO and BRU-FCO-BRU instead of SFO-FCO-SFO.

The way the itinerary looks, they would get into BRU and then have a reasonable connect time - 3-4 hours - before catching their flight to FCO.

What I'm wondering though is if they should be severely delayed on their AA flight into BRU and miss their flight to FCO, is there much likelihood the second airline would allow them to take the next available flight without causing them to buy a new ticket at whatever the fare is that day? They will be traveling on non-changeable/non-refundable tickets on Virgin Express.