Child table field linked to other child table


I have a case to make link to a record of table…I’ll try to give an example:

DocType A
Filed Name (text)

Field Struture (table of DocType B)
Field Items (table of DocType C)

DocType B (child doctype)
Field ID (text)
Field Description (text)

DocType C (child doctype)
Field Name (text)

Field chapter (link to a record of table structure of Doctype A)

I think that If I link Chapter field direct to DocType B, I will get all record in that DocType, but I want to be possible to link only to existing record on table Structure of DocType A.

I hope I have manage a way to explain what I need.


I’m stuck in this situation, can anybody have some clue?