It sounds like you were using the same Apple ID for iCloud, and when she turned on iCloud Photos, they synced to her phone. iCloud is not a storage location, it is a syncing service. And once she deleted them from her phone, it deleted from all devices using iCloud Photos. If she then deleted them from the Recently Deleted photo, they are gone. The photos in iCloud are not backed up when doing a backup, so unless you had imported them to a computer first, they are gone. I'd also have your sister get another Apple ID.
Apple Event: May 7th at 7 am PT
It sounds like you were using the same Apple ID for iCloud, and when she turned on iCloud Photos, they synced to her phone. iCloud is not a storage location, it is a syncing service. And once she deleted them from her phone, it deleted from all devices using iCloud Photos. If she then deleted them from the Recently Deleted photo, they are gone. The photos in iCloud are not backed up when doing a backup, so unless you had imported them to a computer first, they are gone. I'd also have your sister get another Apple ID.
restore your backup from when they were there - that is why you must always have backups - things happen
LN
How do I do that?
No idea - how do you make up your backups? - you restore them based on how you make them
LN
is there any way to find picures after they have been deleted from recently deleted?