Modules & VBA :: Invoice And Subform - Add Multiple Record (Item) At Once

I almost complete my mini project - Stock Inventory:

To track Items enter and exit from Videoshop or simply known as Stock Transaction (IN/OUT). This also include a Inventory Catalog which basically show all the Items in the Videoshop, each Items details including category, transaction type description and most importantly quantity on hand.

As mentioned above, I almost complete the database except the most important Form - New Stock Transaction where User enter all the necessary details to issue an IN or OUT Transaction. To make things easy to understand, it share many similarity with Invoice and New Order.

Code:
Main Form (Table: StockTrans)
Trans_ID
Trans_Type
Trans_Date
Trans_Cust
Trans_Note

Code:
SubForm (Table: StockTrans_Items)
Trans_ID fk
ItemID fk
Trans_Item_Qty

When I finished records entry and enter Invoice completed button then it will auto update the Item Quantity on Hand.