[HerenIstarion]

As far as I know, no other princes or Thranduil's wife are mentioned anywhere. If it may ease your curiosity, Legolas' grandfather was named Oropher (poor comfort, to request for brother and get a grandpa, [img]smilies/tongue.gif[/img] ).

Yet I beleive quest of the ring may be considered event important enough to send the only son and throne's heir to take part in it.

Still more that Legolas was sent to announce Gollum's dissappearence in the first place. Decision to become part of the fellowship was his and Elrond's, not Thranduil's. Yet I can well imagine Thranduil seeing his son off with kind of last words: "Do Master Elrond's bidding, my son" or something os the kind.