What's the GD wisdom on siblings, toys and sharing?

[Calliope]

I'm sure I could scour the forum for appropriate threads, but I really want the down and dirty on this issue in a jiffy. There are three specific scenarios that I'm dealing with right now.

1) R taking away ANYTHING that BabyG has and is enjoying, even if it just a random piece of detritus that R has no interest in playing with himself. I make him return the item in these instances but it still happens all. the. time.

2) R taking away every toy from G because, in his mind, they are all his. I've told him he needs to share or go where he won't be disturbed by G. If he leaves something out in a common area, it's fair game for G to play with IMO. I'm not sure what to do when G wants to play WITH R and R behaves like his entire fleet of Matchbox cars will be tainted or something if touched by G.

3) Yesterday was G's birthday. He received just a few new toys and as soon as G starts playing with one, R commandeers it. He offers to trade G for an old toy (something that I have insisted upon when R wants to take a toy that G is playing with) and flips out when I insist that these new toys are G's and that he gets first dibs on them.


There is more and more screaming from both kids over this toys sharing issue and I'm tired of hearing it. What do I do?