This sample demonstrates how to use a single form with multiple actions in Blazor

Single-form-multiple-actions.razor

<form @formname="updateTodos" method="post" @onsubmit="HandleSubmit">
    <AntiforgeryToken />
    @if (Items is not null)
    {
        @foreach (var (id, item) in Items)
        {
            <p>
                <input type="checkbox" name="items[@id].IsDone" />
                <input name="items[@id].Text" value="@item.Text" />
                <button name="deleteItem" value="@id" type="submit">Delete @item</button>
            </p>
        }
        <button type="submit">Update items</button>
    }

    <p>
        Add item:
        <input name="newItemText" placeholder="Type here..." />
        <button name="addItem" type="submit">Add</button>
    </p>
</form>

@code {
    public class TodoItem
    {
        public bool IsDone { get; set; }
        public string? Text { get; set; }
    }

    public static Dictionary<Guid, TodoItem> Items { get; set; } = new();
    [SupplyParameterFromForm] public Guid? DeleteItem { get; set; }
    [SupplyParameterFromForm] public string? AddItem { get; set; }
    [SupplyParameterFromForm] public string? NewItemText { get; set; }

    public void HandleSubmit()
    {
        if (DeleteItem.HasValue)
        {
            Items.Remove(DeleteItem.Value);
        }

        if (AddItem is not null && !string.IsNullOrEmpty(NewItemText))
        {
            Items.Add(Guid.NewGuid(), new TodoItem { Text = NewItemText });
        }
    }
}