I was taught that the pattern ‘If you should’ is rather formal and is used in the case when a speaker supposes an event (condition) to be very unlikely, just a chance possibility.
If your should see Ann, please ask her to phone me tomorrow.
My question is:
Is If you should equivalent (in the above sense) to If you happen or the latter still means ‘more possible’? Or the latter is exactly the same, but just a bit less formal?