On Tue, 14 Sep 1999, Miller, Bert wrote:

"If I read Tenchi right, just now... hmmm. My little present may
actually do some good. Could break this little amorous stalemate."

For OAV continuity, there is no amorous stalemate, except perhaps
in Tenchi's mind.  As you cite, Aeka and Sasami are from a culture
which allows co-wives (the fanfic sort-of-convention that there's
a Jurai limit of two has no basis that I know of), and Youshou,

Well, we only see the emperor having two wives, though that could just be
because the wives relevant to the situation came.  The semi-canonical '101
Tenchi Muyou Secrets' specifically said the Emperor had exactly two wives.
(It was a book released in Japan in conjunction with the OAVs)

John Biles
Emperor of all He Surveys
http://www.tass.org/~rhea/falcon.html

"He who breaks a thing to find out what it is, has left the path of
wisdom."
     -Gandalf