Nav radio settings in FMC

If you have an FMC flying the aircraft, does it use the same nav
radios you have for your own use, or does it have a separate set of
radios that it uses? Will it use the radios no matter what other
methods it has, or will it use the radios only if other methods (GPS,
IRS, etc.) are not available? Does it mess up the FMC if you tune the
nav radios manually while it is flying the aircraft (other than during
localizer and approach modes)?

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