To link two companies you will use the 'Link Companies' button on the company record that you do not want to keep. 

• First, in Nexa, go to the company that you do not want to keep. 
• Click the Link Companies button
• In the pop up, use the dropdown to select the company that you want to keep
• Click the Link button. 
• All records from the 'Secondary Account' will be moved to the 'Main Account'
• The Secondary account will then be inactivated and hidden from Nexa. It will still existing in the database but will no longer be accessible in Nexa.