There are two different ways you can add individual results to an existing results set.
Make sure to select the Append radio button when adding to existing results.
The simplest method is to put the result(s) into a .csv file and upload using the Upload from File tab. Then just define the column headers, preview and save to the database.
Alternatively, you can use the Paste Text tab on the Upload Results screen and paste or type in the information for the result. then copy that exact row and paste it immediately below the result so that it looks similar to the . You are using those characters to set your column widths for this text paste, select APPEND and define columns, preview and save to database.