You can't have 2 countries set for one ID at the same time. When you relocate, you can change the store you are using for the ID. You should retain all prior purchases, but you may not be able to update them in the other store if the version in the other store is different than the version in the store where you purchased the item. When you relocate again, you should be able to. update.
To change stores, 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 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.
Purchases - Subscriptions not billed through Apple
Region - Change your iTunes Store, iBooks Store, or App Store country or region.
If necessary, contact iTunes Support. Either use the form or scroll to the bottom of the page in the 2nd link. Follow through the screens to get a chat or telephone option.
iTunes Store - Contact Us - Official Apple Support.
iTunes Support – world wide