Inertia 1.0 : How to return data back to controller from Page view

I am trying to pass data back to my controller. I have installed the new Inertia 1.0 . To that end I have entered into the script, import router from '@inertiajs/vue3'. According Jeffrey's tutorial on inertia all should have to do is import inertia into my Vue 3 script and then do an Inertia.post(),

If you use Inertia.post() you get an error in he Chrome console :

Uncaught ReferenceError: Inertia is not defined

So, I changed it to router.post() however, with the new router function nothing is working. I get an error,

export 'default' (imported as 'router') was not found in '@inertiajs/vue3' (possible exports: Head, Link, createInertiaApp, router, useForm, usePage, useRemember)

I post my code below. FYI I am getting all the data through on this.changedChild

Any ideas?? Many thanks!

    <script>
    import router from '@inertiajs/vue3'

    export default {

        props: {
            Children:{
                Children:Array
             },
        },

        data() {
            return {
                active:false,
                inputClass: 'present',
                absentPresent:'Absent/Present'
            }

        },

        methods:{
            updateChild(child){
                this.changedChild = child;
                console.log( this.changedChild);
                this.inputClass = 'present'
                this.active = ! this.active
             
		   Inertia.post('/updateChild',this.changedChild)    // THIS DOES NOT WORK
            },
        },
    }
    </script>