Julian, you can always condense the players into a single staff yourself by copying (or cutting) the music and pasting it into the single staff — you can use the Paste Into Voice feature for that. You will find that sometimes you will need to exclude dynamics, and the filtering options will help with that.
And I assume you can keep everything within one file, although my project was so huge that I had to create a separate file just for the full score with condensed player staves. It’s more of a pain to fix mistakes, but the separation is also good because it means it’s harder to mess up the parts while you’re producing the full score.
If I can assist further, let me know… Good luck!