Seniority question about listing first class vs listing economy

I'm a designated buddy. Been one for years but still have a question:

If I list first class and a higher ranking person lists economy class, do I still get the first class seat even though he/she is higher on the priority list? (because they listed as economy)

I other words, am I "competing" seniority-wise with just the individuals who also listed first class, or does seniority still trump what class you chose to list in?

I realize my lowly position here, at the bottom of the totem pole. I am deeply grateful I can even do this at all, and what would be "right" to me is seniority trumps whatever class of travel you listed in. But I just don't know the answer and am hoping to find out. (Admins: I did do a search for this answer before I posted, couldn't find anything). Many thanks.

Your pass sponsor is always your first and best source for travel and boarding info.