>>285783486
If the tie also has bones in it (named tie 1, tie 2, or whatever) then just parent those to the chest bone. Otherwise if there's no bones select the tie, go into weight painting mode, and under tools there should be a checkbox that says "autonormalise" that you need to check. Then either select or create a vertex group named chest with the same capitalisation as your chest bone on your avatar, and paint over the entire tie until it's fully red. Then join it back to the rest of the mesh and you should be golden.