Master page with detail list issue

Hello everyone,

I'm building a main page with the list of table objects and a sub page (part list) to list relation between table and company (Nav 2015). The Goal is to get a list of table to apply some work in different companies.

The problème I have, should be really simple to solve. I want to be able to fill the TableID field in my Part List with the ID of the selected object in the main page.

I've create a function (local = no) is the part list page to receive the id but the function is not accessible from the main page. In fact, if I use currPage."Part List Page" the compiler tells me that "Part List Page" is not a valid variable.

I did some research in the sales Order Page and sub page but can't find where they fill the "Document No." field of the sales line table. It should be pretty easy to do but I can't figure it out.

Can you please help me?