DB in Access

We use WP for our invoices, customer information and we use Access for invoice controll. (paid, unpaid invoices, customer total and so on).? Now we would like to have everything in Acess.? When we create a new invoice the customer ID number should fill in all the information and should also add all informations to the invoice controll as also deduct the items sold from the inventory list. Till now we used the 2 different programs to do so. Find attached a copy of our invoice, as a description which kind of reports we would like to generate.