Was searching for tickets to Zagreb, Croatia and thought I'd have to book thru CDG being that AF was the only airline in skyteam that flew there. However, my friend found an awesome deal for $700 for MDW-ATL-ZRH-ZAG-FRA-ATL-MDW with travel on Croatia Airlines (Star Alliance member) on google flights. There was a note at the bottom of google flights saying that we had to call Delta directly to book. Indeed, this flight could not be found online at delta.com or other sites like kayak. I called DL, and sure enough it was there and I booked it.

So here's my question. Without google flights how does one find flights like this? Does ITA give you flights like this? My second question is that I only have a 1 hour layover in FRA coming back. If my flight is delayed or cancelled in Zagreb would I talk to Croatia Airlines about just getting me to FRA and deal with the mess once I get to FRA or would I call Delta from Zagreb and see how they could reroute me. I'm expecting everything to be fine, but just wondering how that would all work, especially if I check luggage onto my Croatia airlines flight.