Changing phone number in Apple Account

Check iMessage and FaceTime settings for your device. On an iPhone or iPad go to Settings > Messages > Send & Receive, and make sure both your telephone number and Apple ID are input there and both show a checkmark. If you need more help, check out this link: Add or remove your phone number in Messages or FaceTime --> Add or remove your phone number in Messages or FaceTime - Apple Support

Check your Siri settings to make sure your correct contact information is selected. You can do this by going to Settings > Siri & Search, and making sure that My Information shows your contact card information. If not, tap on it and select your correct contact card information from Contacts. See also: Tell Siri about yourself on iPhone - Apple Support. Tell Siri about yourself on iPhone - Apple Support

Ref. family sharing confusion - Apple Community

To edit your list of trusted items go to the section: About trusted phone numbers and trusted devices in the document Two-factor authentication for Apple Account - Apple Support

To see, add, or change your trusted phone numbers:

- On your iPhone, iPad, or iPod touch: Go to Settings > your name > Password & Security. Next to Trusted Phone Number, tap Edit.

- On a Mac: Choose Apple menu  > System Settings (or System Preferences), then click your name (or Apple ID). Click Password & Security, then add or remove a trusted phone number.

- In a web browser: Go to the Account Security section of https://account.apple.com