[Freesurfer] Getting around a design matrix with zero columns

Dear Freesurfers,

I am studying how the practice of meditation affects cortical thickness. I have two types of meditations, and I also know for how many years each mediator has meditated. Therefore, ideally I would like my categorical factor to be meditation (control, meditation1 and meditation2), and continuous factor to be the number of years of meditation. This design, of course, has a problematic column of zeros, which corresponds to the slope of the control (a non-meditator has meditated for 0 years).

Does freesurfer has a way out of this problem? For example, I have came across pseudoinverse methods in literature?

Any suggestion is highly appreciated.

Thank you very much! Sincerely, Ye