At the most, I think there is one relation here, and it will be a route relation. I don’t think the boards will be part of that relation, but can be associated with it, by adding operator tags.
There isn’t enough information to be sure that even route relations are appropriate, but if they are, it would be advisable to ensure that they are signposted on the ground, as their verifiability may get challenged, otherwise.
It is always acceptable to split a way if different parts of it have different attributes, and that includes being and not being in a relation.
Incidentally, I note that you are adding English changeset comments in Austria. Whilst it is good to see useful comments, there is no requirement that they be in English, and if you know German well, German would be more appropriate in that place.