i do notice that when someone send a message to selected multiple people, there's no reply to those same people.
is that desirable? stops unofficial cliques i imagine.. official cliques have official message groups and their "reply to list" bit..
That is intentional. The game intentionally limits who you can communicate with, and the way in which you do so. Say, for example, a guild elder sends messages to selected members, including some aspirants. Guild Aspirants are not allowed to selectively choose recipients in the guild, so a Reply-to-List link would let someone use a reply style that the system intentionally denies them from using.
This ability to control communications, and arbitrarily group nobles is one of the primary features of guilds. If this ability was granted to everyone, without the need for guilds and guildhouses, then guilds would become mostly superfluous. This is why the Contacts list only lets you send messages to one noble at a time.
If we let you select individual nobles from different lists, and then gave everyone "reply to list" links, then we might as well jsut give everyone a list of all nobles on the island, and let them pick and choose from that.