I'm trying to filter a view 

I have a system of class like this :

class GrandParent(models.Model):
    [...]

class Parent(models.Model):
    grand_dad_id=fields.Many2One('GrandParent')
    children_ids=fields.One2Many('Child)
    [...]

class Child(models.Model):
     dad_id=fields.Many2One('Parent')
     [...]

And when cliking on a grandParent kanban card I would like to display his "family" : his grand children (class child) grouped by parent
I don't know how to acess the "grand_dad" property.
I tried something like :
<record id="view_child_search" model="ir.ui.view">
[...]
<search string="User Stories">
<!-- <field name="dad_id.grand_dad_id"/> -->
[...]
</record>
With in the action on the grand_parent card :
{'search_default_parent':active_id}