Hi Munchmunch
Your 2 sound quite like ours sometimes, when it comes to 'sharing' toys (though not treats luckily). When Dyl joined our family, I had limited experience about 2 dog familys, and I must say I defo made the mistake of reuturning Dyl's stolen toys to him after Clive had pinched them. Im sure now that this encouraged Dylan to bark extensively after Clive nicked a toy, he's probaby saying 'mum! he did it again, get it back for me!' because he quickly learnt that's what I Did do
. Dogs don't think like we do, but they do learn veruy quickly that a behavious will get a certain reaction.
So, these days, like Rachel says I either leave them to it, and if I have to deal with Dyl's barking. Or if its causing annoying levels of chuntering I put the toy away altogether, then no-one gets it. And the toy is not taken away in an angry way, but eithe rin a bright and breezy 'toys away now' way, or as a trade to the one involved.
I think you dealt with the tea towel incident well, by backing off. Like Mark said, guarding against people needs sorting out pronto, so if you can do find a good local behaviourist. If it helps, separate the dogs while they have their chews, just to ensure there are no problems. You don't want this to get worse while you help Jess sort out her guarding issue.