Linking two data tables without a common field

Hi all

I have an existing PBIx staff dashboard that covers general employee metrics, plus absence, turnover etc. 

I have now been asked to add in an additional section that focuses on our employee training compliance. To that end I have added the Learning data table that comes from our HR system. I have managed to link the "People" data table with the "Learning" data table so that a table will show all the courses completed next to the employee name.

So to get to my question, I have attempted to bring in in the Unit Structure data so that I can organise compliance data by our reporting units. With the existing dashboard visuals there is an obvious link to join tables together, PersonKey, PositionKey, UniStructureKey, but with the new section when I try and add in Unit Structure data I am presented with an error asking me to fix the link between the Person data and Learning data. Unfortunately there is no common field that links the two together.

So I am ideally looking for suggestions on how to link these together (if its possible) so that I can create an expanded dashboard that includes learning information. 

(At present DimUnitStructure links to FactWorkForceMonthly (via UnitStructureKey) and that then connects to DimPerson (via PersonKey))

Please let me know if you require further ifnromation, and apologies for the long post.