If I have one Apple ID but have an iPhone and an iPad but do not want the photos on the one to be mixed with photos on the other how do I backup to my partners iCloud package? Ho does the partner invite as when invite happens it is the Apple ID
iCloud Backup of multiple devices with the same Apple ID are automatically kept separate by device.
Also see: How to back up your iPhone or iPad with iCloud - Apple Support and View and manage iCloud device backups - Apple Support
That is different than iCloud Photos which is a syncing service. Photos are automatically combined for all devices using the same Apple ID that are synced with iCloud Photos. There is no option other than that for devices that are using the same Apple ID.
Note that you can view the contents of iCloud Photos at www.icloud.com but you cannot view the contents of an iCloud Backup.
All of the above is true whether you are using your own iCloud storage plan or a plan that is shared with your partner. See the following from Share iCloud+ with your family - Apple Support
When you share an iCloud+ subscription, everyone in the family group uses their own account. That way your photos, documents, and other information stay private, even though you're sharing access to the service. You simply share the features and space available in iCloud+ with your family members, so you only have one plan to manage.
iCloud Backup of multiple devices with the same Apple ID are automatically kept separate by device.
Also see: How to back up your iPhone or iPad with iCloud - Apple Support and View and manage iCloud device backups - Apple Support
That is different than iCloud Photos which is a syncing service. Photos are automatically combined for all devices using the same Apple ID that are synced with iCloud Photos. There is no option other than that for devices that are using the same Apple ID.
Note that you can view the contents of iCloud Photos at www.icloud.com but you cannot view the contents of an iCloud Backup.
All of the above is true whether you are using your own iCloud storage plan or a plan that is shared with your partner. See the following from Share iCloud+ with your family - Apple Support
When you share an iCloud+ subscription, everyone in the family group uses their own account. That way your photos, documents, and other information stay private, even though you're sharing access to the service. You simply share the features and space available in iCloud+ with your family members, so you only have one plan to manage.
Separation of two devices on one iCloud
