It can be done but you would really need to be careful ...

1 Backup your database before doing this ...

2 Recheck the database tables in case I missed anything

Note: the field for the customers_id may vary but it will start with "customer" in most cases ...


You need to change the customer_id from the Customer A to Customer B in the tables ...

address_book
- change customers_id from Customer A to Customer B

coupon_email_track
- first change customers_id_sent from Customer A to Customer B
- then the emailed_to email address from Customer A to Customer B email address

coupon_gv_customer
- combine amounts and remove Customer A to Customer B

coupon_gv_queue
- Change Customer A to Customer B

coupon_redeem_track
- Change Customer A to Customer B

customers
- remove Customer A

customers_basket
- remove Customer A

customers_basket_attributes
- remove Customer A

customers_info
- remove Customer A

orders
- change Customer A to Customer B
- change customers_email_address Customer B email

reviews
- change Customer A to Customer B

I have not attempted this in a long time and you will have to determine if you completed all updates correctly ...