Seed collection can play various roles in ash conservation. Depending upon whether there are sufficient male lingering ash present at a site, collection of seeds from female lingering ash can be especially useful, because these seeds may pass on some heritable EAB resistance, although not nearly as reliably as scion (twigs used in grafting) from these trees.
If you are considering collecting ash seeds, very useful materials are available at this webpage on seed collection produced by the Ash Protection Collaborative Across Wabanki (APCAW). Although some of the information on it is specific to Maine, much of it consists of general guidance that will be useful regardless of your location.