My wife and I are trying to plan a trip to the Lapland region next March. I've found potential itineraries via ITA but can't find the similar routing via AA oe via Finnair's site. So I figured maybe it was a difference between a third party site and the individual carriers.

However, using the oneworld flight search tool, it also shows the routing I want and has the "click to book" icon. That launches AA's site and once again AA returns "no match found". Is it common that oneworld's flight search returns unbookable itineraries or is this a case where AA's website is wrong and I should just call?

On a related front, I can price out and book two separate tickets and it appears to be cheaper than what ITA shows as the cost of a multi-city routing.

My preferred routing is DFW-xxx-HEL-RVN where xxx could be FRA, LHR, CDG etc. Then RVN-HEL for so we can spend a few days in Helsinki and then return HEL-xxx-DFW.

I can book DFW-xxx-HEL-xxx-DFW as the bookends and book HEL-RVN-HEL as a separate ticket. I assume I would be unprotected on the first HEL-RVN segment if the DFW-HEL runs late. Right now I would have a four hour layover in HEL to clear customs, get bags and recheck for the HEL-RVN segment. If I go this route, what should I be aware of?

thanks

Tom