Custom Credit memo transaction type not showing in subscription profile

The above credit memo transaction type is created in AR, however in subscription profile this is not showing up- please check below subscription profile screenshot.

Does subscription profile not allow custom 'Credit memo' transaction type?

Business is looking to send miscellaneous credit lines via subscription to the customer as goodwill and for other reasons. This will be a new separate subscription for that customer (apart from one orginal subscription for services) specifically only when miscellaneous credit needs to be sent. And this miscellaneous credit line that will be coming from this subscription into AR must create a Credit Memo transaction for the customer. Can such case be possible via subscription management? How ?