FRS, as well as GMRS, frequencies are in the main database under "Nationwide Systems".
In Sentinel, open up the US portion of the main database by clicking on the + ('plus') sign.
Then, scroll down to any state & county & click the plus sign again to open the county.
Click on Nationwide to open it. There, you will find FRS, GMRS, and other systems that are in use across the U.S.
On the scanner itself, if you set the 536HP to scan the Full Database (under the 'Set Scan Selection', 'Select Lists to Monitor'), then you can choose which 'Nationwide' systems to monitor, or to ignore.
If that's not what you are trying to determine, be a bit more specific as what you are trying to do.