[Harlowe][Twine2] Is it possible to set a value in a Datamap to a reference to a different Variable?

I'm starting to learn Twine, and I thought I'd go about making a small framework to familiarize myself with the system.
What I'm trying to do is set up a Datamap called "Door" that has a key/value pair of "openCondition",$doorUnlocked.
Now what this does is set "openCondition" to whatever $doorUnlocked was when "Door" was created. That's fine, but what I need is "openCondition" to be a reference to $doorUnlocked so that when $doorUnlocked changes, "openCondition" changes as well.

Is this something that can even be done in Harlowe? If so how?
If not, does it work in Sugarcube or any other format?

Thank you for your time.