GMRS Radio use at NASCAR race

Total newbie here. I have two TDRADIOS H8 sets and two Rugged Radio headsets. I understand how to listen to the Nascar radio broadcast frequency.

What I am trying to figure out is how my wife and I can communicate with each other while listening to the radio broadcast.

I see there is an A/B switch. Do you have to switch frequencies?

Any instructions would be great.

Thanks in advance!

My tdh3 allows me to listen to vhf FM radio 87mhz to I dunno 108mhz. I can tune to my favorite fm radio station on the ht and listen along and when the radio picks up an incoming two way signal it will automatically mute the fm “music”I’m listening to and open for the incoming two way radio traffic so long as it is on the same a or b band as my tdh3 is set at. So yes. You can do that.