Custom column value in Gantt

We are facing issue -
We have added 2 new custom columns plannedstartdate and plannedenddate.
if task is unscheduled then, these column values are empty.
We want to fill the values for these two custom columns, at the same time we do not want to fill start_date and end_date and duration for these tasks.

Thanks & Regards,

Hello Sweeti,
You can use the template in the column config and return the date string if there are dates.
Here is an example: