@aviator-p, volunteerpilot.
I think CTC have made a mistake here so I would ignore them. It clearly states on BA's website that this is not possible.
"No. You must decide at which of the three FTOs you would like to undertake your training before you commence your application. We therefore recommend that you visit the websites of all three approved FTOs and study their offerings carefully. For clarity, if you are not successful in the selection process at your selected FTO, it will not be possible to apply to either of the other two FTOs in this application window."