Josh,
Many thanks for your message -- warmly appreciated!
Yes, your description is accurate. After posting my message, I realized aspects may be specific to the Codex MezzaTheme. In a dump of the MySQL dbase, I see:
REPLACE INTO `codex_portfolioitem` (`id`, `_order`, `portfolio_id`, `content`, `title`, `href`, `featured_image`) VALUES
... followed by the content of the associations. While I suspect there are both Python and MySQL (PostgreSQL, etc.) ways of doing this, am I correct in gathering a SQL query of the existing page items, followed by a SQL insertion of said items in association with the new page "copy," may be the current "state of the art?"
Warmly appreciated!
Brygg