Finally, I found a way to manage this, downloading this module:

https://www.odoo.com/apps/modules/7.0/one2many_sorted/

Then, I overrided the one2many whose order I want to alter, in my case the field was child_ids, and I wanted it to be ordered by email:

'child_ids' : one2many_sorted.one2many_sorted(
    'res.partner',
    'parent_id',
    'Contacts',
    order='email',
)

Note that the only difference between this field and the one2many is the param order (you can use a couple new more though, search and set).

I also imported the library at the top of the file:

import one2many_sorted

Now, I'm seeing the tree and kanban of res.partner ordered by name, but this one2many is ordered by email. Great!