Doctype Referencing (Data Migration)

I have created a new doctype called Cash Requisition . I have put a button To the Purchase order, Purchase Invoice, Payment Entry.

I want when i click Purchase order some data that are both in the cash requisition and the Purchase order to auto fill but also it should be seen in the reference in the puchase order and purchase invoice


I need help please

Reference: Adding Custom Button To Form

Reference: [HELP] How to Customize (hide) "+" add button in section Connection (Linked Documents) - #3 by NCP


I have created buttons as you can see, how can implement that?

Please check the video.