I'm going to create above mapping.need to many2one fieds & if i select company then need to come to second combo relevant estate for that companies.please help me to sort this issue.

I checked 'related' filed type also in developer guide.but haven't idea to implement in that way.check this code & advice me to sort this issue. thanks

class bpl_company_registration(osv.osv):
    _name = "bpl.company.registration"
    _description = "BPL Company registration"
    _columns = {

                'name': fields.char('Company', size=50, help='Company'),
    }

bpl_company_registration()


class bpl_estate_registration(osv.osv):
    _name = "bpl.estate.registration"
    _description = "BPL Estate registration"
    _columns = {

                'name': fields.char('Estate', size=50, help='Estate'),
    }

bpl_estate_registration()

class bpl_division_registration(osv.osv):
    _name = "bpl.division.registration"
    _description = "BPL Division registration"
    _columns = {

                'name': fields.char('Division', size=50, help='Division'),
    }

bpl_division_registration()

class company_estate_division(osv.osv):
    _name = "bpl.company.estate.division"
    _description = "Company Estate Division Mapping"
    _columns = {
        'bpl_company_id':fields.many2one('bpl.company.registration', 'Company', help='Company'),
        'bpl_estate_id':fields.many2one('bpl.estate.registration', 'Estate', help='Estate'),
        'bpl_division_id':fields.many2one('bpl.division.registration', 'Division', help='Division'),
        }

company_estate_division()

Another method

class company_estate_division(osv.osv):

    _name = "bpl.company.estate.division"
    _description = "Company Estate Division Mapping"
    _columns = {
                'bpl_company_id': fields.function(_get_company_data, fnct_inv=_set_estate_data, type='one2many', relation='hr.department', string="Company"),
                'bpl_estate_id': fields.function(_get_estate_data, fnct_inv=_set_estate_data, type='one2many', relation='hr.department', string="Company"),
                'bpl_division_id': fields.function(_get_estate_data, fnct_inv=_set_estate_data, type='many2one', relation='hr.department', string="Company"),
        }

company_estate_division()