Setting up Roku remote with brand new Hisense Fire TV

I am trying to set up my Roku remote so that, in addition to controlling my Roku, it can also control my Hisense Fire TV.  I have a different Roku remote for a different Roku that works with the Hisense TV but it belongs to my son.  That remote worked with code 13.  With my Roku remote, I can only go up to code 7, at which point it no longer continues the pairing process.  Any assistance with this would be welcome.