Can I merge or change an account from one country to another one?

You can change your existing Apple ID account and information from one country to another.

You need a zero account balance and you need to cancel all your subscriptions. If you have cancelled all subscriptions, but some haven’t expired, contact iTunes Support. You need a valid credit card issued by a bank in the country the store is in and you need a billing address in that country. If you have an account balance, either buy something more expensive and pay the balance with a credit card or contact iTunes Support and ask them to zero balance your account.

Purchases - View, change, or cancel your subscriptions.      *

How to cancel Apple TV+.  *

Purchases - Subscriptions not billed through Apple    *

Link to contact Apple Support at the end of the article.

Purchases - the subscription that you want to cancel is not listed    *

Region - Change your iTunes Store, iBooks Store, or App Store country or region.     *

If you have done all the above and are still having problems, contact iTunes Support. See the Apple Support articles below for contact information.   

iTunes Support – world wide   -

Apple Support schedule phone call     -

Billings and Subscriptions   -

Apple on Twitter  - 

Unfortunately, there is no way to merge AppleIDs, irregardless of the country.

The closest you you can get is Family Sharing, and all members of a family need to be in the same country/region.

See:

Change your Apple ID country or region - Apple Support

and

Set up Family Sharing - Apple Support