Welcome aboard. I’ve moved your post to our UL forum, brighter lights - bigger marquee.
As far as your question, I’ m not with UA but I strongly urge you to nix the buddy pass self-listing idea – too many pitfalls. Besides buddy pass riders, especially new ones, never understand the nuisances of flight selection/listing and what makes for a viable backup - Plus you always want to know the who, what, where, with your passes AND, it’s probably against company policy, which could be why you don’t see the option. *wink*