Can you make a UHF handheld work with a basic 2-way family FRS or GMRS radio (type you can buy from walmart)?

most UHF radios require the frequency to be programmed by an FCC certified technician. Most likely the tech would refuse to program a channel that the equipment/operator is not licensed to use. that would be the case here. if you can get a copy of the software used to program the UHF radio, you might be able to hack the codes for channel selection.