google sheets – create data validation (pulldown) from other spreadsheet

I have current spreadsheet (named as INPUT). In this INPUT , i have a sheet named USER. I share USER sheet to other users so they can write data on it (as editor). On cell A1 , i will use data validation /pulldown from other spreadsheet (named as DATA).

The data validation can’t use data directly from other spreadheet so in the INPUT spreadsheet , i create a new sheet (named as DATAIMPORT) and use importrange() to import from DATA.

It works fine but the DATAIMPORT sheet is visible to all my users. How if i want the hide the DATAIMPORT from my users?