如何显示Vue JS中嵌套在父``router view`中的子``router view`的组件？

<template>
  <div>
    <h1>父级组件</h1>
    <router-view></router-view>
  </div>
</template>

const routes = [
  {
    path: '/parent',
    component: ParentComponent,
    children: [
      {
        path: 'child',
        component: ChildComponent
      }
    ]
  }
]

<template>
  <div>
    <h2>子级组件</h2>
    <router-view></router-view>
  </div>
</template>

const routes = [
  {
    path: '/parent',
    component: ParentComponent,
    children: [
      {
        path: 'child',
        component: ChildComponent,
        children: [
          {
            path: 'grandchild',
            component: GrandchildComponent
          }
        ]
      }
    ]
  }
]