You can only have one trip connected to your pass. But your journeys don't have to be connected with each other. You can add random rail journeys all over Europe. How you bridge the gaps (plane, ferry, walk, hitchhike, coach) is up to you.

Thanks so much for the fast reply! I tried on the app there and I can’t seem to get a train at all anywhere for Barcelona - is there an issue with the app? I’ve seen a few reports?

In Spain are missing some trains in the app, because the spanish railways RENFE, didn’t send them to the European Timetable Center. You can check on the website of Renfe for the trains and add them manually to the app. 

Please note, that most trains in Spain needs an additional reservation.

The rail planner app is very incomplete for Spain. Please check trains via the RENFE website.

FROM airprot in BCN local trains, named Rodalies, leave from a bleak terminal via a long overheated tunnel from the old Terminal (now 2), ev 30 mins to all stops in town, incl. the main station SANTS. THese trains are non-reserved, there are gates, go to counter, show pass, tell, they will open 1 gate for you. To exit at Sts-or anyother-again approach staff near gates. Both Ts also have a brand new metro, not taking passes, and with no direct line into town=change somewhere. Or there is the fast aeropuerto bus.

To use ANY longer distance train anywhere in ESpana, you must make REServation and pay (wait in line, brush up spanish, perhaps after waiting-that awful feared thing for USAers- be told to go to another counter and wait again), get a ticket for that which is the REServation-this has to be used to open gates next trip. The superfast AVE trains also have airline style luggage checks and often also still checks on your covid-pass. You still for now also have to fill out a PLF incl covid-vaccine to enter ESpana-airline may refuse you without.

Thank you so much for the reply! I appreciate the help.