Transfer iCloud photos and videos between Apple Accounts with Family Sharing

My family has an Apple Family Sharing subscription, and I am currently part of the family group. I previously had an Apple Account that contained over 5,000 photos and videos stored in iCloud.

Recently, I changed phones, but unfortunately, I forgot the password to my old Apple Account. Because of this, I created a new Apple Account, which I have been using for the past few weeks. I actually prefer using my new account because it feels much cleaner and more organized, since I was able to start with a blank slate.

However, I am now trying to figure out how I can transfer the photos and videos stored in the iCloud of my old Apple Account to the iCloud storage of my new Apple Account. I would like to keep using my new account while still being able to access and preserve all of my photos and videos from my old account.

Additionally, I would like to use the larger iCloud storage available through my family's Family Sharing subscription with my new account.

For clarification, both my old Apple Account and my new Apple Account are already members of my family's Family Sharing group. I would like to know if there is a way to transfer or move the iCloud photos and videos from my old account to my new account while continuing to use the Family Sharing iCloud storage on my new account. I would also like to point out that I now have access to my previous Apple Account.