good evening,
since the creator of this design is also on TH, I might suggest that the original buyer send a note to this person on the website they bought it.

some people might prefer a Toyhouse-based credit to confirm the design is not stolen, so that might help you to trade it.

Oh hi! I didn't realise you were also on TH, or I'd have credited you here in the first place :) I traded for this design with acedaimon on FA last year, but I'm not sure if they're still active. I can send you screenshots of the conversation if you would like to see proof? :) 

since you are not the original owner, I would like to have a proofing of this conversation since while I know that I watermark my stuff, I dont know what the buyers do with their files. I can also send them a message to see if they respond and can confirm the trade

Sure :) I've never had to do this before, is this sufficient? https://sta.sh/2a7waqtpv4h?edit=1

There's no images, but I hope the conversation tells you enough. If not, it looks like AceDaimon is still online at least once in a while on FA, though they're not very active it seems. 

it does indeed.

thank you for your patience. It should get a bit easier to trade this character now.
have a good day

No problem! Thank you for pointing it out :) Have a good day!