if you can see clear 'space' between the clumps then use a sharp spade to slice through the clump. this will allow you to lift a section with out disturbing the rest of the plant. Try to keep as much soil around the roots which is why i'd use a spade and plant to a similar depth.

Thanks SBG. From what you say, I might be able to take two clumps. Brilliant. So glad of this site.

or even 4 if they are clearly visible. :o)
I love plants for free.