I think, there is nothing to be worried about if someone use your referral link to join the forum. But if you don't want to share your ref link to others, the you don't need to share your link to others. Sometime it may happens mistakenly. Example- i gave my ref link to some one to register in the forum. My ref link suppose 4004, the new user typed in the ref box 4040 mistakenly. Then it becomes other referral instead of original link provider. I might be wrong.
