If you want to issue some changes on your existing BOMs, but you want to avoid creating the work orders for them from the start and would rather adjust the existing ones short term, you have an option to do so.
Start creating your BOM based product, from any of the four given ways:
the product itself
inventory > products and services> open the wanted product from the list> go to the create button and choose 'work order'
From the fulfilment list
manufacturing > fulfillment> check the box in front of the wanted item> bulk action > work orders
From the sales order
sales > sales orders> create new/ open an existion one> generate > work order
From the work order list
manufacturing > work orders > create > based on -BOM
Once you've created the work order based on bill of materials and saved it, you will see that the system will not allow you to issue any changes, because this type of work order follows the product recipe that you entered in the product level.
In order to make the necessary changes, you need to click on the 'convert to' option on the right- hand side of the screen.
Once you've confirmed that you want to convert to standard, go to edit mode and you will see that your work order has become editable.