I know that a matching function of some type is
already on the wish list. Here is an alternate
idea that might be of some value.

How about a link on each personal data page
"Look for this person in other databases"

(Kind of long -- maybe a binoculars image with
the above as an ALT?)

Such a link would display a WC detailed search
form (the one that appears on the bottom of
search results) with all the fields pre-filled.
Searcher can then edit and/or click search.