Hi @Yenthe

Take as example website settings and their use of related on settings fields

------------------------------------------------------------------------------- Changes---------------------------------------------------------------------------------

# -*- coding: utf-8 -*-
from openerp import models, fields, api
from openerp.osv import osv

#Import logger
import logging
#Get the logger
_logger = logging.getLogger(__name__)

class Settings_holder(models.Model):
    _name = 'outlook.sync'
    sync_calendars = fields.Boolean('Sync Odoo and Outlook calendars', default=False)
    sync_contacts = fields.Boolean('Sync Odoo and outlook contacts')
    default_backwards_sync = fields.Integer('Months of backwards syncing')
    default_forward_sync = fields.Integer('Months of forward syncing')


class ResConfigOutlook(models.TransientModel):
    _name = 'outlook.sync.settings'
    _inherit = 'res.config.settings'

    outlook_id = fields.Many2one('outlook.sync', string='Outlook')
    sync_calendars = fields.Boolean(related='outlook_id.sync_calendars')
    sync_contacts = fields.Boolean(related='outlook_id.sync_contacts')
    default_backwards_sync = fields.Integer(related='outlook_id.default_backwards_sync')
    default_forward_sync = fields.Integer(related='outlook_id.default_forward_sync')

    def on_change_outlook_id(self, cr, uid, ids, outlook_id, context=None):
        _logger.critical('ON_CHANGE_OUTLOOK_ID')
        if not outlook_id:
            #This means it was never configged - default values here!
            return {'value': {'sync_calendars': False, 'sync_contacts': False, 'default_backwards_sync': 1, 'default_forward_sync': 3}}
        outlook_data = self.pool.get('outlook.sync').read(cr, uid, [outlook_id], [], context=context)[0]
        values = {
            'sync_calendars': outlook_data['sync_calendars'],
            'sync_contacts': outlook_data['sync_contacts'],
            'default_backwards_sync': outlook_data['default_backwards_sync'],
            'default_forward_sync': outlook_data['default_forward_sync']
        }
        for fname, v in outlook_data.items():
            if fname in self._columns:
                values[fname] = v[0] if v and self._columns[fname]._type == 'many2one' else v
        return {'value': values}

    def create(self, cr, uid, vals, context=None):
        _logger.critical('CREATE' + str (vals))
        config_id = super(ResConfigOutlook, self).create(cr, uid, vals, context=context)
        self.write(cr, uid, config_id, vals, context=context)
        return config_id

    _defaults = {
        'outlook_id': lambda self,cr,uid,c: self.pool.get('outlook.sync').search(cr, uid, [], context=c)[0]
    }

I create a view, action and menu for test it

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>

        <record id="view_website_config_settings" model="ir.ui.view">
            <field name="name">Website settings</field>
            <field name="model">outlook.sync.settings</field>
            <field name="arch" type="xml">
                <form string="Configure Outlook" class="oe_form_configuration">
                    <header>
                        <button string="Apply" type="object" name="execute" class="oe_highlight"/>
                        or
                        <button string="Cancel" type="object" name="cancel" class="oe_link"/>
                    </header>
                    <div>
                        <field name="outlook_id" invisible="True" on_change="on_change_outlook_id(outlook_id)"/>
                        <group string="Synchronise">
                            <field name="sync_calendars" />
                            <field name="sync_contacts"/>
                        </group>
                        <group string="Outlook settings">
                            <field name="default_backwards_sync"/>
                            <field name="default_forward_sync"/>
                        </group>
                    </div>
                </form>
            </field>
        </record>

        <record id="action_outlook_configuration" model="ir.actions.act_window">
            <field name="name">Outlook Settings</field>
            <field name="res_model">outlook.sync.settings</field>
            <field name="view_mode">form</field>
            <field name="target">inline</field>
        </record>

        <menuitem id="menu_outlook_configuration" parent="base.menu_config"
            sequence="90" action="action_outlook_configuration"/>

    </data>
    <data noupdate="1">
        <record id="default_outlook" model="outlook.sync">
            <field name="sync_calendars" eval="True"/>
            <field name="sync_contacts" eval="True"/>
            <field name="default_backwards_sync" type="int">1</field>
            <field name="default_forward_sync" type="int">1</field>
        </record>
    </data>
</openerp>

As you see on the end of the xml there is the definition/creation of the record to be updated in the settings view, the one obtained from the _defaults for outlook_id and passed to the onchange. I test it and it's working