Create a new related entity in a to-many relation field

Double checking whether or not I’ve encountered a bug here.

I am setting up an automation in my contractor invoices database where one contractor invoice can be linked to multiple expenses in the expense database. However in Fibery automations I am not seeing an action where I can create a single expense that is linked to the contractor invoice by clicking a button.
The only action I’m seeing is to update all the entities that are already linked to that contractor invoice. Why is that?
I could have sworn this feature already existed.
Looking for guidance here as to whether this is a bug that it is missing or this is actually a feature request somewhere.

There should be an action called “Add [database name]”.

Maybe it’s a lookup or an autolinked relation?