HOW TO SYNC BETWEEN TWO DIFFERENT FILES

How do I set up two Numbers spreadsheets, one the original and the other the follower, WHEN THE TWO SPREADSHEETS ARE IN DIFFERENT FILES?

My issue has arisen because my IPhone SE(2020) cannot handle a lot of sheets with formulae and the file crashes, while my IPad Air(5th Gen) can handle the same file with multiple sheets and complex formulae. So, to work on the file on the move with my IPhone, I have had to create a new file with only the sheet I need to work on, which reduces the load and the IPhone works without it crashing.

This ends me up with two files on my Ipad - (1)the original & (2)the new file with only one sheet and I open only the new file on my IPhone.

Therefore the need to sync that one sheet with the original file on my Ipad with the changes I make on my IPhone or IPad on the new file.