I have 3 models: `User`, `Receipt` and `Article`. 

Only association is: Receipt `has_many` Articles.

Now I need 4. model, which is `Company`. User belongs\_to company, and Company has\_many Users. 

User needs to see only Receipts and Articles that are in his Company. 
Do I need to have company\_id in User, Receipts and Articles and browse by that id, or there is a better way?