Save data from two diff forms to mysql db

Hi i have the following app in process, basically its a stock transfer creation, so i will move Product XYZ from warehouse A to warehouse B, and the right table its a temp working table in mysql to save current products before creation, and when i click Green button (Save & generate) i should save all info like: date, status, ref number, warehouse from, warehouse too, and the info of the added product in the right table. And all that will be saved to 4 diff tables in mysql, how i can achieve that?

also your opinion, the left table it can be like hidden? so only show product when i search using the search field? right now im query select * all my product table, but that will be bigger like 100k products i dont want to show any product, like this video where it uses a select box and then user modify quantity and so on:

when i found a product it always put quantity 1 (how i can do that?)

pd: also im not sure how to control, if i have 2 users at the same time creating new stock transfer, if im using one tmp working table in mysql, app will be crazy when it saves :frowning:

thank you