Prevent Contacts associated to a Customer to be automatically attached on Opportunity, Estimate, Sales Order, Invoice creation

When creating an Opportunity, Estimate, Sales Order or Invoice, Contacts attached to a Customer gets added automatically on the transaction (Relationships tab > Contacts subtab).
 
This happens when creating the transaction from the Customer record or from Transactions > Sales.
 
To prevent this from happening, use the quick add portlet to create the transaction. To do this, perform the following steps:
 

1. Navigate to Home > Dashboard.
 
2. In the Settings portlet, click Personalize Dashboard.
 
3. Under the Standard Content box, click Quick Add.
 
4. In the Quick Add portlet, click the Setup icon to set the Type (e.g. Opportunity).
 
5. Click Save.
 
6. Fill out the form.
 
7. Click Save.
 
8. Locate the transaction created (e.g. through the customer record or by navigating to Transactions > Sales > Transaction type > List).
 
9. Check the Relationships tab > Contacts subtab to verify that no contact was added to the record.

 
Note: Customize the preferred form to add Quick Add fields. Enhancement# 131030 has been filed for the Ability to select contacts from a drop down to attach instead of all of them showing up.