Is it customary for a Brown Scapular to be worn alone, or with medals attached? Specifically , I guess, the Miraculous Medal or St. Benedict’s Medal? Or does anyone wear something else on their scapular?
Scapular use is subject to the desires of the local customs.
In different parts of the World, different people have a variety of “Rules” about wearing “accessories” on their scapular.
Even within the area that I live, there are 4 organizations which promote the wearing of the scapular, and each has its own idea of what is proper (and what is not proper) to do. This does NOT mean that you must follow the local practice, but it is a good way to fit in.
So, when in doubt, personally ask the person in charge of your local organization.