Limit Multi-select picks to one in linked table

Pretty simple. 

I have Lot #'s (a lot of them). I have hundreds of inventory items (flavor powders) and each one of the flavor powders have many lot numbers. 

Example: Ingredient Inventory of Sherbet Flavor Powder of 60kg. That inventory may have 3 Lot #'s -
(12kg) #123
(30kg) #456
(18kg) #789

If I choose Sherbet Flavor Powder in my ingredient list (for a recipe), and I need 35kg, I will be using 2 lot numbers.

I would like only the Sherbet Flavor Powder Lot #'s show in the multi-select.