Here is how you can link inventory items to modifiers:
Step 1: Click on 'Menu' on upper left corner
Step 2: Click on 'Inventory Management'
Step 3: Select the item to which you want to add modifiers
Step 4: Click on add variant or unit
Step 5: Click under sublist it variant price and details
Step 6: Scroll down and select the modifier set
Step 7: Click on update
Step 8: Click on 'save' on upper right corner of the screen
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