Is it possible to use a stash variable as a parameter further down the template.
{exp:stash:set name="logged_in_user"}{screen_name}{/exp:stash:set}
{exp:freeform:entries form_id="0" site_id="0" search:foo="{exp:stash:get name='logged_in_user'}"}
{freeform:field:branch} <br/>{screen_name}
{/exp:freeform:entries}