This may be quite a dumb question, but I'll happily put my hand up to being fick, innit, but ...

... how do I change the location of a RAW file without affecting Lightroom's ability to find it?

The reason for asking is that when I first started using Lightroom, I set up three folders, Family, Projects and Comedy to store my RAW files. Under Family I then set up sub folders for each month but since I've started usign Lightroom I realise that this wasn''t necessary and in fact I should simple store all my family shots in the folder Family. How can I transfer the files with the monthly sub folders into the main folder without having to delete from catalog (sic) and re import?