Can Endnote show one field OR another? (Field Substitutions)

Hi -Is it possible to customise field substitutions?

Many imported citations now have both DOI and a (maybe stable) URL.

There is an option to show URL if DOI is missing; but to save editing all templates (with URL specified), it would be good to be able to say if DOI is present, do not use URL

I would make this suggestion in the suggestions forum, as it isn’t currently a substitution option and they do not appear to be customizable.