The Federal Trade Commission (FTC)regulates the Care Labels sewn in garments.
I wouldn't be surprised if the FTC or the government agency responsible for customs and tariffs would have something (of a legal nature) to say about changing the labels indicating the Country of Origin Labels you intend to sew into those garments.
I don't believe that anyone can regulate the Brand Label sewn in garments. For example, men's and ladies boutiques routinely sew in their own labels into garments branded by other for that "aura of exclusivity".
Your'e say that your'e looking to start a clothing company. Yet, by your questions, you clearly know very little about the clothing business and have very limited start up capital (can't afford a plane ticket to China to scout potential production facilities?). If you believe that success in the clothing business is strictly a function of the brand label sewn in a garment, may I respectfully suggest that you invest your time in some other endeavor.