Hi and welcome to ESO addon development.
As katkat42 has alreay told you there is an addon which uses the guild note method to transfer information between guild members:
http://www.esoui.com/downloads/info7...archNotes.html
Merlight builds a kind of identifier string that will be stored inside the guild notes and wil be read by other users using his addon to show the information at crafting stations again.
But the note is not very long and if the information should only be viewable by guild admins/guild officers you cannot assure it this way, I guess.
And in additon the guild members cannot use the guild note to inform others about their name, likes/dislikes etc. anymore.
An idea:
Perhaps you can build an addon that will encode the guild note information (enabled/disabled and manually entered in the settings of the addon for each of the 5 guilds) in such a unique identifier too, so you can use it for your guild members (they all need the addon then) to show the guild information about each member, and in addition the admins/officers of the guild see extra info that you want.
You could realize it with a custom tooltip (on mouse enter of the guild note) for the guild where the addon is enabled for in the settings, instead of showing the original guild info tooltip then.
This way, if it works, you can build a tooltip with the information that you like to have it in (show the main character name + class icon, level etc.).
The information can be automatically be updated for each guild member as he/she logs in/logs out/reloads UI.
And maybe even make it compatible to Merlights addon mentioned above.
If your addon is disabled for any of the 5 guilds the standard tooltip will be shown.