The parameters of the vue child route override the parameters carried by the parent route

my parent route itself carries the parameter aa
but the child route in it also carries the parameter bb, but the aa in the path will not see
http://localhost:8080/-sharp/index/1 (1 is aa) this address will have a page and there will be a child route jump in this one. What I want is http://localhost:8080/-sharp/index/1/12 (1 is aa 12 is bb)
but every time he clicks, he jumps to http://localhost:8080/-sharp/index/12
every time the parameter aa in the parent route is missing
Why is that?

Click the jump code:

<router-link :to="item.bb" >{{item.name}}</router-link>

routing:

{
      path: "/index/:aa",
      name: "index",
      component: index,
      children:[
        {path:"bb",name:"detail",component:detail},
      ]
    },

then I tried to add append to < router-link >, but the first time it was OK. If I ordered something else, it would be wrong

.
Mar.21,2021

aa needs to add
< router-link: to= "/ index/demo" > {{item.name}} < / router-link >
demo is equivalent to aa
< router-link: to= "/ index/:aa" > {{item.name}} < / router-link >

< H2 > and aa is taken in this way this.$route.params.aa < / H2 >

{

  path: '/index/:aa',
  name: 'index',
  component: index,
  children:[
    {path:'bb',name:'detail',component:detail},
  ]
},

the name,component here is taken as this.$route.query.name, this.$route.query.component

so the problem that the parameters of the vue child route override the parameters carried by the parent route
does not exist

.
Menu