Can't add missing credit cards transactions

Greetings: using Quicken Premier for Mac. I'm missing several months' worth of transaction from last year. I can download them from the credit card site but when I try to add them to Quicken, it doesn't recognize the account and won't let me link them to the credit card account. It gives me a list of accounts but it doesn't include the account the transactions are from. Only other option is to add it as a new account and then maybe copy them over--which I have not tried because I'm hoping to avoid having to clean up duplicates. Just hoping for a cleaner way since this seems like a fundamental thing the software should do. Thanks!