I am also a season ticket holder for Wisconsin women's volleyball.
During the NCAA volleyball tournament, the first two of the three weeks the matches are held at 'campus sites'. The first weekend the top 16 seeded teams host three other schools. And the second weekend, the top four remaining seeds host three schools. Unlike this weekend's WCHA final four, there are blocs of seats reserved for fans (friend and family) of those participating schools. But far from your "at least half", those blocs are maybe 100 seats per school.
As for NCAA WH Final Fours, I've been to three. I do not recall there being any bloc of tickets set aside for fans or season ticket holders of the participating schools. If Wisconsin makes the Final Four this year, we can check if such a bloc is offered this year.
As I pointed out earlier, the number of tickets sold last year at Ridder - including for a Wisconsin-Minnesota semi-final - was less than the capacity of LaBahn.