Salesbox has multi relations so you can connect different accounts to each other, contacts to multiple accounts and also the relation between different contacts. 

How to set an additional relation

1. Go to the account or contact you want to connect to another object

2. Scroll down in the right side panel

3. Click the plus sign on multi relations

4. Select the object to connect to and add what type of relation is is

Add new types of relations

1. Go to company settings

2. Select Default values

3. Expand the account or contact relations in the Multi relations section and click the plus sign to add a new relation type