Pull multiple values through a lookup

I am rather new with SP so I apologise if I cant express myself too well.

Problem at hand:

Two lists - Shops and Managers with a many-to-many relationship between them.

I.E. in Shops there can be more than one managers and a manager can manage more than one shop

I want to either:

1. Create a List C where I have a lookup column listing each shop in the first column and in another ALL of the managers that correspond to this shop, written in one line.


2. Insert a column in Shops outlining all of the managers per a particular shop.

Essentially I want to create a workflow that is activated on a specific date, which checks whether there has been any change in the Managers or the Shops list and subsequently update List C.

Any idea on how I can get multiple values for a lookup?

I created the workflow, but I can only have one value per a field in Shops for managers.