Is there a way in NetSuite to mark orders that must be fulfilled to the extent of the quantity available? Meaning, when I create the Item Fulfillment, it will only default to the available quantity. The Global Accounting Preference isn't applicable in our case because sometimes we need to fulfill orders regardless of the available quantity.

It sounds like you looking to ignore commitment without setting the preference to ignore commitment?

Yes, ignore commitment for some but fulfi based on commitment for others