Forms :: Auto-update Date Field

Is it possible to automatically update a date field in a form record without ever clicking in to that date field, but only because you have altered something else on that individual form record or an embedded, linked subform record? eg1. Staff details record - a) create a record for Bob Smith and 'Last Updated' field automatically inserts date b) amend record to say 'Robert Smith' and 'Last Updated' field changes to show new date, even though you never touched that date field. eg2. Risk register - main form record contains name, details, and 'Last Updated'; embedded subform allows you to add individual records of actions taken for each risk. I want the 'Last Updated' field to update each time I add an action, without amending the 'parent' risk record.