When you have a secondary organisations linked under your primary account, you have an option to share the contacts with them easily. 

To share or link the contact:

1. Go to Contacts --> Search for the contact to be shared under “Name search” -- > Select the contact -- > Click on Open -- > Click on “Share contact” on the window.

2. Now, select the Secondary Organisation from the drop-down list

3. Click on "Share contact" and Yes, the contact is now shared with the secondary organisation.