Apparently InterRail-planner does not show regional trains on FS lines in Alto Adige, that are operated by SAD (e.g. Brennero-Bolzano-Merano). As SAD and FS are cooperating on these lines in a traffic and tarif cooperation it should be normal, that you could use either train (FS as well as SAD) also with an interrail-pass, If not, that would mean, that you would have a train only every second hour instead of each hour.
I understand, that Interrail is not accepted on Merano-Malles as this is now an SAD infrastructure. On the line of Val Pusteria (Fortezza-San Candido) it is less evident as this should still be an FS infrastructure but operated only by SAD trains (when not closed for works).
But I think, it should be accepted on Brennero-Bolzano-Merano.
I would be happy to have an answer about experiences in 2025!
