Notes disappeared after Apple ID switched

In your system preferences > iCloud sign out from the personal apple id and click on keep copy ( just to save the data for this id as it should not be lost ) , then again sign in with family Apple ID and password , make sure notes , safari ...and all boxes are checked except back to to my mac .

Open your upgraded notes Upgrade your Notes app - Apple Support and let the application be opened for an hour , with high network speed all notes will get downloaded in the respective iCloud and the account used ( could be gmail or yahoo ) that was used to configure with iCloud server .

Read this article Use notes from your Internet accounts on Mac - Apple Support

If you keep notes in Internet accounts—for example, iCloud, Google, Yahoo, or AOL—you can add those accounts to Notes on your Mac, and access all your notes in one place. You can view, add, and edit notes in the Notes app on all your devices that use the same accounts, and your changes show up everywhere—so you always have your most current notes at hand.

Depending on what version of the OS you are using, sign back in with the family ID, and allow time for the notes to sync from iCloud. Then go to Notes/Preferences and check Enable the On My Mac account. Select On My Mac and click the + to add a new folder. Copy the notes to the new folder and then go back to your new ID.

If you are using an older version, try clicking new folder to create an On My Mac. Then go back to the family ID and do the above.

iCloud content is linked to a Specific Apple ID - when you switch to a different Apple ID you switch to a totally different set of content

LN