I've spent 4 hours reading the forum and I am still not clear about how to book a stopover. My understanding is that it is usually allowed on international flights, but don’t see how to add it without a huge jump in fare price. Let’s say I want to fly to Moscow from IAH and on the way back stopover for 4 days in FRA (common connection city). A normal round-trip IAH- MOW is around $700 on ITA, but when I go under the multi-segment trip and start adding an additional segment in FRA, the price jumps to $1600. Any suggestions? How can one search only for fares that allow stopovers? Thanks a lot.