I'm not sure what you mean by this. About new markings, it would be nice to have some new ones. About "create", people can make their presets and markings, so I'm not sure what you're saying.
You can already do this, really. MM3, or Mass Markings 3, is the most commonly used marking pack downloadable from the website. You can upload your own markings as well, thoigh I'm not skilled in that field.