VB6 application for Whatsapp management -- 2

I'd to make small software to allow users to sends and receives WhatsApp messages inside our current VB6 application. VB6 source code of current application cannot be shared. No C#, no Java, no third party controls, no compiled objects. Deliver this project should be with source code only... to enable us to implement the source-code inside our software. Final EXE or DLL project is not important (but via source code). In case of DLL, a .Net compliance must be guarantee. The final user is a company that manage BUS. To do it, he use a VB6 application done by me 10 yrs ago (Damages, allocations, customers, ...) Now, he wants to add a WhatsApp functionallity (inside the actual application, not outside) to call the bus-drivers, send messages, maps pictures, .... and receive by the bus-drivers feedbacks, news, new opportunuty, .... For example: * to driver1= give us your position * to driver2= send a picture of damage * to driver3= write your driver licence code .... See the attached schema. No new graphical interface needed. This means that I ask for VB6 source code, not compiled. Points of attention: bus-driver are more than 2, this means that new VB6 function has to manage 3 (or more) whatsApp number/account in the same application (problems with login/auth process WITHOUT using QR CODE and INSTANCE_ID, CLIENT_ID, CLIENT_SECRET) No urgency. Start as soon as possible - daily update is requested, to avoid time loss and misunderstandings about requirements. No upfront. No payment before successful completion of all tests. Source-code required for test. Bonuses are provided at the end of the project for compliance with the timing and quality of the software.