Squelch adjustment might help in that situation (only if the signal strength of the chatter is substantially lower than that of the wheeling group radios), but "Privacy Codes" is a better solution. Here's some more information on the difference, although you'll see they are related because they both affect the radio's way of handling squelch:
Squelch Control Adjustment
As I alluded to earlier, this changes the minimum signal strength required for the radio's receiver to listen to a signal and present it to you through the speaker. This control is especially useful for when you are hearing static, but can also work when chatter is from more distant radios. Adjust your squelch to ignore it. Back in the haydays of CB, the squelch control was a knob, just like volume. It was necessary because CB signals are different (AM and lower frequency - so much so that quarter-wavelength antennas are not very practical). As a result you heard a lot of static. It was easy to adjust squelch. When you heard static, you just turned the knob clockwise until the static stopped - done. With GMRS radios, very few have a knob specifically for squelch control because it's not nearly as necessary with the cleaner signals. If there's no squelch knob, you have to figure out how to change it, and some radios are very cumbersome, but typically, you're selecting a number from, say, 1 to 9, to set the squelch. So, to adjust it while receiving static, it's takes much more time. I wish more GMRS radio manufacturers would use a squelch knob.
"Privacy Codes"
As previously mentioned, you can use "Privacy Codes." That's in quotes because, as many people know, it's not really giving you privacy (any radio not using Privacy Codes will hear all transmissions, Privacy Coded or not.) There are two forms of these codes - digital and analog. I won't explain the difference between digital and analog here because I think it's become somewhat common in our computer-influenced lives. Guess what? Both of these methods also deal with squelch control! In fact, in their acronyms, there is a S that stands for squelch. The digital method is known as Digital Coded Squelch (DSC) and the analog method is known as Continuous Tone-Coded Squelch System (CTCSS). How does it influence the radio's squelch control? The transmitting radio is set to transmit on an inaudible frequency, a digital or analog signal, along with the audible (voice) transmission. If the receiving radio has the same "Privacy Code" set, it will only "break squelch," or present the transmission to you through the speaker, if it detects this inaudible portion of the signal. So, again, it's important to understand squelch control. If you don't have CTCSS or DSC enabled, the radio's squelch control doesn't filter any transmissions out - you hear everything. Again, this is why using the word "privacy" isn't exactly true.