Carol_Hill said:
...travelling on one way tickets. You should have that regardless. That is a different question to me, than whether you can check in online or not.
I do not think it is. When we used one way tickets we could not check in online, as the airlines are required to check for a return ticket. I was told SXM required it.
The airlines online check in does not have the ability to check for return flights on different carriers, so if you are using one way tickets, you must check in with an agent at the airport. At least, that was my experience.
