def METHOD_NAME(self, parser):
    for name in ("run", "variants"):  # intentionally omitting "multiplex"
        subparser = parser.subcommands.choices.get(name, None)
        if subparser is None:
            continue
        sparser = subparser.add_argument_group(
            "JSON serialized based varianter options"
        )
        settings.add_argparser_to_option(
            namespace="json.variants.load",
            parser=sparser,
            long_arg="--json-variants-load",
            allow_multiple=True,
            metavar="FILE",
        )