Hello. Thank you for contacting the Toolset support.
What child element you want to add and exactly where?
Can you please share as much information as you can with admin access details and problem URLs and let me review and check what could be the possible option available that could help if any.
*** Please make a FULL BACKUP of your database and website.***
I would also eventually need to request temporary access (WP-Admin and FTP) to your site. Preferably to a test site where the problem has been replicated if possible in order to be of better help and check if some configurations might need to be changed.
I have set the next reply to private which means only you and I have access to it.