Hello, I am asking for your help after 5 days of searching through the forum, youtube, etc..etc ...

I have the following scenario

I want to generate an invoice realted to a custom module, these being linked through a lookup field. Both in the invoice and in the custom module I have other common lookup fields for Account. In addition, there is a common field of the multiselect type (it's Tehnicieni in foto Attached) and fields for address (Billing City, Street, etc...). I want all this to be autocomplete when I initiate the invoice from the custom module. Below are 2 print screen.