thank you shreya, do appreciate the help, but have tried this and the only option is adding 2 adobe id's - they don't recognise the old one. any other suggestions??
You can try multiple activation on ADE if you are using it on Windows or Mac.
1. Click on the ebook thumbnail in library which is authorized by old adobe id
2. ADE will prompt you to enter the credentials with which book was downloaded.
So now ADE has multiple activations done