How to do different different instruments on a different page?

Let's say in the first movement I want 2 violins and a trumpet. But two pages later, in the second movement, I want just one violin, and a trombone. How can I do that?
(I want to do Beethoven IX, and the instrumentation changes from section to section.)
So is there any way to have some instruments, but some time later, have completely different instruments instead of them?