diff --git a/odoo/addons/base/models/res_partner.py b/odoo/addons/base/models/res_partner.py
index 83d14da10e3..d110cb3598f 100644
--- a/odoo/addons/base/models/res_partner.py
+++ b/odoo/addons/base/models/res_partner.py
@@ -515,6 +515,8 @@ class Partner(models.Model):
                     if len(companies) > 1 or company not in companies:
                         raise UserError(
                             ("The selected company is not compatible with the companies of the related user(s)"))
+                if partner.child_ids:
+                    partner.child_ids.write({'company_id': company.id})
         result = True
         # To write in SUPERUSER on field is_company and avoid access rights problems.
         if 'is_company' in vals and self.user_has_groups('base.group_partner_manager') and not self.env.su: