Monitor windows queue printer, and for each job received, show and allow customer to sign with a signature pad

I need a software component to enhance our current printing and signing solution. Our current situation is the following: • We have a windows program that, for each customer that enters in our shop, takes care of capturing all the information associated with customer and the products that he/she is going to buy • After the program has all the information, it creates an invoice and send a copy to a windows queue printer, and the invoice is printed in paper (2 copies) • The customer signs the 2 copies, and he/she takes one with him/her and the other copy is kept at the shop We would like to change our process so, instead of the customer signing the 2 paper copies, he/she signs in a signature pad (like a Wacom or equivalent device). We could change our windows program to include the functionality to use a signature pad, but it is an old program that is not easy to change. So the alternative we are evaluating is a W10 program that does the following actions: • We install a new computer (Windows 10) with this new program that monitors the windows printing queue (remote or local printer going through standard Windows spool/printing queues) • Each time the program finds a new job in the queue, it will show the document in the computer screen, and will activate the signature pad • The customer can see the invoice in the screen, and one he/she is ready, will sign the document using the signature pad, and then the program: o Will create a new document that merges/combines the original document plus the signature o Prints one copy for the customer o Creates a PDF version of the new merged/combined document that also would include a digital signature using the digital certificate of our company, and stores the document in a file server on in an sql server (as a BLOB), with a given name/key • Once all the previous task are done, the program will return to an idle screen where it will keep monitoring the queue for a new job to arrive and repeat the above steps