As we all know, most standby tickets are issued in Y, but occasionally it is also possible to get standby tickets issued in C class. For instance: my airline has an agreement with LX (carried over from the good old SN/SR times) allowing us to get standby tickets in business class on SWISS. Whereas this is obviously great, it also makes things more complicated to understand (at least for me)

I've used it once so far and it worked great, but then the flight wasn't full (not in C nor in Y) so there wasn't any real chance for any problems with it, but it has made me think about what would have happened if things were less than ideal?

My question is thus double:

1- If I recall corectly, my staff office issued our STBY travel tickets in C class with LX as ordinary ZED tickets to give us more flexibility, rather than as an ID95 (or whatever) ticket on LX alone; if I'd used the ticket on another ZED carrier however, would I then also get a business seat (provided there is one available obviously) since that is the class I was standing by for, or would I automatically have been downgraded to Y, even with C class seats available and the corresponding ZED fare paid for it?

2- Where am I in the priority list?
If Y class were overbooked and C class had open seats, would I still get the seat as a C class standby pax, or would they upgrade a full fare Y class pax and drop me in Y (or even worse: leave me behind!)?

Thanks for any meaningful replies.