Just seen these, caro, they are I am afraid right, sorry - collies are working dogs, although 1000's of people have them and find them to be fine but personally I would not rescue a collie.
Suggestion - you ALL have to be firm with him when he does things like this, it will be no good if one or several of the household giggle or reward him when he does it, someone needs to be firm to begin with and tell him "NO". If he responds well, give him a titbit. Gradually all try it until he gets the message. You have a lot of work on your hands and I think if you work hard, you could possibly turn him around but everyone has to pull together and work hard at it. Make sure your GS doesn't get left out in the process! If you feel you need a bit of extra help, you can always find a dog handler through your local vets or yellow pages, or try the internet. It would be nice, a year from now to sit back and say "just think, we nearly got rid of him" but you have comitted to him now so do try hard. ES