Export to sub domain to standalone domain

You would clone the database, and then write a custom script to:

-- Find all nodes _not_ assigned to 'all affiliates' or to the subdomain.
-- Delete those nodes, using node_delete().

Then uninstall Domain Access and all its submodules.

Your query for part 1 would be something like so, assuming we want to save domain 4.

SELECT nid FROM {domain_access} WHERE realm = 'domain_site' OR (realm = 'domain_id' AND gid = 4);

You can do something similar to users by looking in the {domain_editor} table. There is nothing to do about files, which are not separated per domain.

See section 7 of README.txt for developer notes (including schema definitions).