good news, everyone! I just received an e-mail from Evgeny, whom we have contracted for AskBot improvements, and it's now possible to merge questions.
Here's what he writes:
"on questions there is a button "merge"
when it's clicked, a modal menu opens where you
enter question id,
this loads preview of the target question
once confirmed, merge occurs.
Question bodies are spliced,
also answers are spliced if one answer per user is allowed.
This means that it will be required to edit the question body and
possibly some answers. This editing is not part of the merging workflow
and the admin will have to do this separately."
Let me know if this works and if you have questions.
Thanks, and thanks especially to Evgeny!