
Hi Kaushik,
The recommended modern approach is option #1 create a Custom Page (Canvas App) and call it via JavaScript using Xrm.Navigation.navigateTo() when the user clicks Close as Lost.
It gives you a rich UI for capturing additional details (dropdowns, text boxes, reason codes, etc.).
Xrm.Navigation.navigateTo(
{
pageType: "custom",
name: "new_CustomDialogPage"
},
{ target: 2, width: { value: 500, unit: "px" }, height: { value: 400, unit: "px" } }
);