Allow "Web headline" field to be blank when article asset presentation is Long-form

We would like the ability for the "Web headline" field to be blank when an article asset is set to "Long-form" and ONLY IF the asset's "Hammer" field is populated. 

The reason we would like this function is for display purposes. We like the way the Hammer looks with a Subhead, however we are forced to populate the Web Headline field. If we populate it with something like a dash or bullet, that is the headline that is displayed on the website.

Ideally, if an asset's presentation mode is set to Long-form and the "Web headline" is left blank, the article asset would use the "Hammer" field as the web headline. This would open up our online display options as we wouldn't be forced to populate the Web Headline field.