Hi there, @LustofHeaven . Thanks for taking the time to reach out to the Shopify Community here with your questions around your product drops. My name is Imogen. It’s good to meet you!
Based on what you’ve described, it sounds like what you’re trying to do is sell a finite amount of shirts (so 100 shirts) until you run out of stock. You should be able to do this by creating the product within your Shopify admin, and then assigning 100 units of inventory to that specific product. I fear this may be a gross oversimplification of what you’re looking to do, but based on the information you’ve provided, I feel this should help you achieve your goal.
Are these 100 blank t-shirts also being used for other products, or specifically for these dropped products? Is the goal here to have your blank t-shirt inventory apply to multiple products so when all the t-shirts are purchased across all the products that use them, products will then no longer be available for purchase?