Auto populate a field value of sub table in Simple list & Details - List grid form

Hello folks,

I am trying to replicate a form same as Item sales tax group form. Now my query is I am using 2 tables one for the header and one for the lines. Whenever I click on the new button for the lines table, it should automatically populate the pk of the header table. I have added a relation between the two table. However I am not sure how do I achieve this? Can anyone please help me.

Also I see when I go from one item to another in the header table then all of the values present in the lines table is displayed, however this should not be the case.

You already have another thread for your second problem and I already replied there. Please take a look. There is also a good chance that it’ll resolve your first problem as well.