If you're using above mentioned skin wrap, make sure to convert it to a skin modifier if you need to export it; fbx doesn't include skin wrap modifiers. Either way you should end up with a handkerchief that follows the arm.
To elaborate, I have a character with a skin modifier. He wears a handkerchief which is a separate object. When he runs, the handkerchief droops below him and dangles everywhere which doesn't look cool, I want it to stay in place, attached to his chest... but I need to keep the two meshes separate for reasons. So, is it…