Is it possible to have two append queries update the same table?

Currently I have a data entry form that contains a command button that runs
"Append Query 1" which adds new records into "Table 1". However, I have another form (which allows the user to go back into the records they entered in the data entry form and edit them) on which I want to run "Append Query 2". I want "Append Query 2" to update existing information in Table 1 (put there by Append Query 1) with the new changes the user has made.

Currently, Append Query 2 is updating the table but it is not overwriting the incorrect information. It is merely adding new rows with the new information.

How can I get Append Query 2 to over-ride the existing information in Table 1 that was originally submitted by Append Query 1?

(Hope this makes sense. Tried to make it as straight forward as I could).