Use a custom block inside another custom block

Finally,I have found a solution. I can pass my custom block to the InnerBlocks inside a template prop.

    const TEMPLATE = [
        [
            "core/columns",
            {},
            [
                [
                    "core/column",
                    {},
                    [["custom/Block A", { url: "this is a url" }]],
                ],
                [
                    "core/column",
                    {},
                    [["core/paragraph", { placeholder: "Enter side content..." }]],
                ],
            ],
        ],
    ];


    <InnerBlocks template={TEMPLATE} />