Combine multiple spreadsheets on a click.It automatically retrieves all existing sheets in a file. Easily the sheets that you want to combine and get data appended to existing sheet or create a new file. 

Steps:
Go to Add-ons > Combine Sheets > Start to start. it will automatically look for the sheets in your workbook. then select the sheets you want to combine and hit combine button. using this addon you can either append entire data to the existing sheet or replace existing data with the new data. you can also choose if headers are required from each sheet or just first for consolidating data.