This OpenCart related products by Manufacturer module will allow you to quickly relate Manufacturers to each other .
Get related products for OpenCart 3 - CLICK HERE
FEATURES

• Relate one or many to many products at once
  
• Filter products by price range
  
• Relate products by Manufacturer
  
• Relate one or many product Manufacturers to single or many product Manufacturers
  
• Delete Related products for given Manufacturer of main products
  
• - one Manufacturer to many Manufacturers Related products
  
• - many Manufacturers to one Manufacturer Related products
  
• - one Manufacturer to one Manufacturer Related products
  
• - one product to all products by a Manufacturer Related products
  
• - many to many or one products Related products

DEMO
(This is the full demo. In this product you will have only the Price Range and the Manufacturer tabs in Advanced view)
http://ggwshop.com/oc23bulkrelatedultimate/admin/
user: demo
pass: demo

Requires vQmod 2.3+
Installs via the Extension Installer
Old modules compatibility fix for OpenCart 2.3 included. So your older modules (for 2.1 for example) will magically start to work again.
Check the Documentation its a 1 minute read and install process I promise :)