It's your own game, so of course you may set up your own expectations, limitations, rules and whatnot more. Heck, most people wouldn't even think or try to inlude other people's characters, so I think that's a really neat idea.
Kind of like a kickstarter idea. If you pay to back a project they might include your character as well, but also doesn't always happen. I think it's a pretty neat idea to have this fun type of trade going on.
So in the meantime, guys, let's stop bickering and actually provide and recieve help rather than arguing whether or not Benny is in his right to ask for a trade rather than a give-away.