Is it Safe to change the "Field name" for a lookup via the form definition

Is it Safe to change the "Field name" for a lookup via the form definition

I have a fair amount of info in Zhoho at the moment so thought i would ask

I want to change the Field name (refer to another  field) on an existing lookup in one of my forms
There does not seem to an option via the Edit Field properties but i can see how it is declared in the form definition

Has anyone ever edited this directly ?

So far i have been creating a new lookup with the new field and deleting the old existing, however as the existing lookup is tied to Deluge actions it can be a pain as you have to manually edit every instance (nice feature actually)