It was addressed before, but the question was too specific, thus doesn't resolve my issue. I'm expecting a general answer, though provide an example as well.
For instance, I'm writing a letter and attaching some extra files along with important ones. I would write:
I have also attached the original document [just in case/ in case you need it/ …].
What other options can you think of?
Best Answer
Rare is the time when a ‘general’ answer can be given to a question like this. A more formal version of something else will always depend on the context.
In your specific context, I would agree with Andrew that simply getting rid of ‘just’ would make the most neutral and mellifluous phrasing. A few other alternatives could be:
Of course, these rephrasings will not work in certain other contexts; for example, “I have attached the original document just in case” cannot be rephrased to any of the above. You would have to infer from the context whether that should be rephrased to something like, “For the sake of completeness, I have attached the original document” or perhaps even, “Erring on the side of caution, I have attached the original document”.
Only context can tell.