Yes, bra cups can be sewn into a dress. This is a great way to add support and coverage if you are wearing a dress with a low neckline. It is also a good option if you do not want to wear a traditional bra. When sewing bra cups into a dress, it is important to use a seam allowance that is small enough so that the cups will not shift or move around inside the dress. You will also need to reinforce the stitching at the top and bottom of the cups so that they stay in place.