BCS_Race_Series_Sponsor_2017

Can I switch from one race distance to another?

Runners may switch between races (i.e. from the marathon to the half marathon or vice versa) up until one month before race day (November 10th) for a fee of $15. No official distance switches are available after the November 10 deadline. If you switch during the run, you may not receive the finish medal or shirt until those who finish the proper distance all receive theirs.  

See the entire answer