Brilliant!

(The lambs are coming home ... and other snatches of carols...)

I presume in the finished version the blue and red dots become invisible - other than that, it works exactly I I envisaged.. though you are going to have trouble getting all those sheep in those two pens!

Do the sheep become 'inert' once penned - or is there a risk of attracting then out of the pen while you pen another? In the simple version, it would be easiest if they stay put once penned. Can that be done? Put them in a 'dead spot' once penned?

It's lovely! I'm hopping about with excitiement!