Use existing field as foreign key or populate created foreign key using existing data

I'm an Outsystems noob and feel like this scenario should be fairly common, and that I should have already found a KB/how to article to answer the question, but I haven't (maybe I've used the wrong search criteria).

I have create two tables by importing two excel spreadsheets. Table 1 contains a lookup list of values which can be found in a 1:many relationship in Table 2. 

The problem is, that when I go to create a relationship between the two tables in the Outsystems Data Model, rather than use the existing field in the Table 2 for the foreign key, a new field is created.

I have already tried removing the ID field in created Table 1 after importing and setting the imported lookup field as the primary key, but this didn't change anything.

If this process can't be changed the alternative is to populate the new foreign key in Table 2 with the actual foreign values, but I'm unclear on how this can be achieved either.

Any thoughts/guidance would be appreciated.

Both tables after a fresh import with pre-existing lookup values/related foreign keys circled:

Scenario after relationship created (existing data in "JobName" field ignored)..


Found it: