PHP/MySQL - Add automatic lot sequencing to existing data entry form

We have an existing PHP data entry form that accepts a few values from users (Item, Lot Number, Label Qty, etc). Currently the Lot Number field is defined by the user for all items. When a user enters an item number and a label quantity, the defined lot number repeats on every label in that print job (Example: 10 labels with Lot Number 12345) Items are currently being displayed in a drop down menu which is generated from a MySQL table. We would like to add a feature to this form so when an item is selected, the page knows if it is a "Kit" item or not (this value is defined in the item table along with every item number). If kit_item = 'Y' then the Lot Number field should be hidden from the form (or disabled) and the lot numbers for the requested labels should be generated dynamically from a sequence. Both scenario examples: Method 1: Non-Kit Items (current functionality) User defines a label qty of 10 User defines a non-kit item (Item1234) User defines Lot Number (9876) 10 labels print for Item1234 all containing lot number 9876 Method 2: Kit Items (New functionality) User defines a label qty of 10 User defines a kit item (KitItem4567) Lot Number field is disabled automatically when item is selected 10 labels print for KitItem4567 - each with a unique Lot Number 001 - 010 We can define a table for this that can hold the starting sequence number and use for tracking of these numbers going forward. Or if you have a better way of doing this, we are open to suggestions. The simplest and most elegant solutions are best. With the existing functionality (Method 1), a single record gets inserted into a MySQL table since the lot number is the same for all labels in the request. For Method 2, I expect a loop will need to be used to insert a single row for EACH label in the request, each with its own unique sequenced lot number.