My rules for having my adoptables and designs traded are that they need to come back to me ideally first, or to have the option to buy them back. 

I've had a few instances where I find my work retraded without consulting me.

Today I found one traded away from that who got it, who is now trading it again. This is honestly really hurtful for me as an artist. Please always pay attention to an artist's rules when adopting something or consider these things. I make note of this stuff because I put a lot of time and effort into my designs and seeing one so recently traded off, then traded off again really was the last thing I wanted to see.