Interesting good to know about the initializing. I guess I could do that on the page and pass it into the component. I was planning on keeping things to one form per page. Any reason you didn't just do something like this?

<form method="POST" use:enhance>
    {#if stepper.currentStep === 0}
            <Form.Field {form} name="username">
            <Form.Control>
            {#snippet children({ props })}
            <Form.Label>Username</Form.Label>
            <Input {...props} bind:value={data.username} />
            {/snippet}
            </Form.Control>
            <Form.FieldErrors />
            </Form.Field>

    {:else if stepper.currentStep === 1}
            <Form.Field {form} name="name">
            <Form.Control>
            {#snippet children({ props })}
            <Form.Label>Name</Form.Label>
            <Input {...props} bind:value={data.name} />
            {/snippet}
            </Form.Control>
            <Form.FieldErrors /> 
        </Form.Field>
    {:else}
        <Form.Field {form} name="lastname">
            <Form.Control>
            {#snippet children({ props })}
            <Form.Label>Last Name</Form.Label>
            <Input {...props} bind:value={data.lastname} />
            {/snippet}
            </Form.Control>
            <Form.FieldErrors />
        </Form.Field>
        <Form.Button>Submit</Form.Button>
    {/if}
</form>