Corresponding phones
I just recently upgraded and whenever I add contacts on my phone they go on my daughters phone, also my iCloud number is my daughters phone number
iPhone 11 Pro, iOS 13
Question marked as
This is because you and your daughter are signed into the same Apple ID for iCloud and is designed behavior. That said, you should stop sharing accounts immediately, because Apple ID accounts are not meant to be shared. Each of you should be signed into and have your own Apple ID. All that is required to create one is a valid email address. If your daughter is a child under 13, then you can create an account for her using Apple's Family Sharing features which you can learn more about here.