- 🇳🇱Netherlands megachriz
It looks like this use case would fit better in the Rewrite plugin. There's a feature request to add an option to the Rewrite plugin to only rewrite if empty: ✨ Rewrite value using another field value only if empty. Needs work
Recently, also a Twig plugin was added (to the dev version as of now), so you could also use that one for conditionally setting values too.