Get custom codes used in transaction receipt (renewable subscription)

Issue

Currently I have multiple subscription offers available for yearly/monthly subscriptions. Each of the subscription offers have multiple different custom codes available. When the customer buys a subscription and the receipt is being handled in the backend, I need to know which of the custom codes was used.

What I have tried

When i call the https://buy.itunes.apple.com/verifyReceipt I get the values offer_code_ref_name and promotional_offer_id. The offer_code_ref_name is the subscription offer name AND NOT the custom code.

I tried to get more info using the https://api.storekit.itunes.apple.com/inApps/v1/subscriptions/{transactionId} request, but it does not give me any info about the custom code used either.

I do however see which custom code has been used if I go to Sales and Trends > Sales and Trends Reports and download Subscritpion Reports. There the offer code can be found ref. as "Promotional Offer ID"

my question

How can I get which custom code was used when purchasing a renewable subscription using transaction id or transaction Receipt?

Can you file a feedback assistant ticket with example custom codes, transactions (JWS or app Receipt) and responses form any of the server endpoints? http://feedbackassistant.apple.com Please reply with FB# once filed.

Get custom codes used in transaction receipt (renewable subscription)
 
 
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