I use a sheet to keep track of service requests that are entered via a public form.  One of my customers wants to use an API from their system instead of filling out my public form.   They want to directly create rows in my sheet from their system, and we have tested this and it works, using Zapier.   

BUT, I'm not keen on providing them with access to my "production" sheet and would like to use an intermediate sheet as a buffer between their system and my "production" sheet.  They would add rows to the buffer sheet, and then I need a way for that row to be automatically created/copied into the production sheet.   The column structures will be identical.   What is the best way to achieve this?