Easy. He was married to Goldberry, the River-daughter, and Lalaith was a river-daughter as well, being named after the stream near Húrin's house. (Besides, you should remember from the Maedhros thread that Goldberry was in fact Lalaith reborn as a Maia!*
)
But how's this for a game idea: somebody suggests a Tolkien character, and the other players have to link this character to Lalaith in some way or the other (can and should be humorous);
Urwen decides who did best, the winner gets to suggest the next character, etc. Would that appease you,
Urwen?
PS. (*Oh yes, and Tom himself was of course Sador Labadal reborn, hopping along in his yellow boots to conceal the fact that he still had a wooden foot.)