Here's how to append data to an existing data source: 

 The "Append Data" function allows you to add data to an existing dataset. For example, if you had a hydrant dataset in your Maps site, and then you installed some new hydrants, the data for those new hydrants could be added/appended to the original hydrant layer.

In order to append data to an existing layer, you need to first ensure that the number, type and name of all fields in the new data match what is already defined for the layer's original data source. 

1. Open the LAYER ADMIN panel. 
   
   
2. Click the Data Sources tab.
   
   
3. Choose your data source. 
   
   
4. Click "APPEND" in the "Data" section of the data source information. This is to add new data to the existing data source. Keep in mind that this newly appended data must have the same number, type, and name of fields as the original data.
   
5. Upload the new data, and click "APPEND". The new data will now be added to your original data source.