Hi, Moustafa.
You can’t add data to TinyDB ( last data store are there ). But can store TinyDB data into in a variable and add data to variable and last store this into TinyDB. I hope that it should be understood what I mean.
More easy:
If you store on tag “user” the values 1, 2, 3 and next store on the same tag the values 4, 5, 6. When you get TinyDB value of tag “user” you get only 4, 5, 6.