Hello,
Based on your query you can access a manual method for backup Thunderbird contacts by replacing address book from parent account to other. For that, follow the steps given below.
- Open Thunderbird profile. Go to Address Book icon.
- Select the address book which you want to export then click Tool >> Export
- Choose the storage location and Select CSV format. click Save button.
Now switch to another account where you want to export the contacts.
- Then click Tool >> Import >> Address Book.
- Select the text file from the window and open the csv file from the storage location.
Likewise you can import address books to new profile from here you can access the contacts.