How can I stop the format changing when I copy data into an unlocked cell in
a format protected worksheet?

I need to allow people to both enter data or copy data from another source
into cells so I have unlocked these cells but also don't want the format of
the cells to be changed. If you enter data directly the format does not
change but if you copy and paste data it changes the format.

I know you can use "copy paste special values" but would like to know if
there is some system way of doing this.