MarketKing 1.5 introduces a 'Product Bundles' module. This allows each vendor to configure and sell bundles, based on the functionality of the WooCommerce Product Bundles plugin.
For vendors to be able to manage bundles, this module must be enabled in MarketKing -> Modules:
Also, importantly, if you allow vendors to create only specific product types you will need to add 'Product bundle' to the list in MarketKing -> Vendor Groups.
With this feature, enabled, each vendor can go to the vendor dashboard -> Products and create bundle products:
Vendors can create different kinds of bundles, choose a min and max quantity of each product, choose whether each product is priced individually, etc.