Personal User Information viewing

I’m making an app for my family to track our spending by using ‘girl maths’ to divide the number of uses of the product by the product’s price (stemmed from an inside joke).
On the main sheet, I am creating a page where they can see Family Items and Personal Items. Therefore, in the Personal Items section, they need to be able to add and edit items as they please without the information becoming accessible to anyone else.
In the future it would be useful if they had the option to ‘give’ the item to someone else, or make it Family Items so only having one data sheet seems logical? I just don’t know how to do it.
I assume there is some sort of function that when a user adds information, they can select whether it is Personal or Family. Help would be much appreciated!!

I would have just one table, and differ items by a “Type” column, where you can choose the value to be “Family” or “Personal”.

Make sure you record the user’s rowID when they add a new item.

Add an if-then-else column named “Visible”. If “Type” is “Family” then true, if “User ID” is signed-in user’s ID then true.

In your Users table, add a query column, target the Items table, filter by “Visible” is checked. Show that list to the user.