Additional data can be added to already existing layers using the tool, Bulk Add.
Note:
Column names must be the same as data field names, otherwise data information will not transfer
Steps
Right click on desired layer to add excel data. Click Bulk Add.
2. Name not necessary to fill. Click Choose File.
3. Import Type will automatically change to Excel. Fill in Latitude and Longitude.
4. Click Upload.
5. "File data added successfully" green message will appear. You did it! Data has been added to layer.
Feel free to reach out if you are experiencing any errors in this process.