Hi,

1. About Model inheritance

First of all, are you sure you really need "_inherits" ?
It is much more common to use "inherit" which works like this :
_name = 'child1.child1'
_inherit = ['parent.parent']
And then you can use the field of the parent in the child object :
child1.parent_field

If you don't know the difference, see e.g. :

https://www.odoo.com/fr_FR/forum/how-to/developers-13/the-different-openerp-model-inheritance-mechanisms-what-s-the-difference-between-them-and-when-should-they-be-used-46

2. About parent / child relation :

This is not related with inheritance but to relational fields.

In that case you can have :

- a One2many field in the parent model to its children

example : child1_ids = fields.One2many(comodel_name='child1.child1', inverse_name='parent_id')

then you can do:

for child1 in parent.child1_ids:

    ... do smth ...

- a Many2one field in the child object to its parent (that must then be called 'parent_id' to correspond to the 'inverse_name' used before)

see for example the link between a partner and its contacts in native Odoo.

And explanation of relational fields :

https://www.odoo.com/fr_FR/forum/aide-1/question/relational-fields-114056