Double check-me ... I'm not seein the expected value from this operation.
set-qadgroup $group -SecondaryOwner "dom\user1" - appends value instead of replacing existing
set-qadgroup $group -SecondaryOwner @{clear=@()} - does nothing
set-qadgroup $group -SecondaryOwner @{append=@("dom\user2")} - appends value √
set-qadgroup $group -SecondaryOwner @{delete=@("dom\user2")} - clears all values instead of just the targeted user
Create an array of values works as the parameter for set-qadgroup -secondaryowner instead of replacing the existing value - it adds the new value (appends) rather than replacing as was the prior behavior