Hello everyone please need your help

i have a 2012 Mini Cooper s Hatchback i am looking to change the tail light to union after market light and also my bumper comes with the brake and reverse light as one

i am also looking to change my bumper to JCW version and JCW comes with brake light only

my question is how can i get the union lights to work as reverse light also using new JCW bumper (that doesn't give me option to use reverse light )

hope you can understand what i am asking for sorry my English not the best