Originally Posted by Koby

Nobody seems to know, so I’ll try to help (a bit)...

There are 2 many elements that I don’t know to give you a full answer. But one important element is that your flight, although coming from MAD, is treated as a non-Schengen flight at FRA. This is important for the immigration question.

But you should tell us where you fly on AB (Schengen, non-Schengen) to get a complete answer. And can you get your boarding pass for AB online before leaving MAD?

For the luggage: I know that AB interlines with some companies, although they are a LCC. But I don’t know if they have an agreement with LAN. I would ask LAN about this.

In any case, unless you will have your AB boarding pass + luggage is sent through + you are flying to a non-Schengen country (and therefore no immigration in FRA) this looks like a very tight connection.