I found an easy way to work around this problem...

I used Merchant (Commission Shop) in Lightholt Village for my test.
Every item is for sale by a player, clicking items will yield their owner's name.
Clicking player name gives their info including their guild affiliation.
Clicking the guild name then allows for it to be applied to (have your alt do so!).
Have your main character accept the application -no muss, no fuss