Editable Grid

Hi All,

I have a requirement like the

• user can map multiple fleet types & cost for 1 equipment.
• we are displaying the picker field where the user will choose equipmentId from some master table, they can select 1 equipmentid at a time.
• then an editable grid will be displayed below, to add/modify fleet types & cost.

Now the challenge is i am getting index issue during save, 

• If there are any existing mapping for respective equipment id, then when user selects the same equipmentId from picker, then editable grid should display existing mappings and user can add new rows also. If not, then user can add new mappings. For existing mapping they can change the cost alone or JE type alone, which needs to refreshed.
• Also when they not change the cost type, then instead of adding new row in DB, update in existing row for other field like dollar amount,updated by,updated On
• If they removed existing cost type, then change is_Active = 0 for those rows in DB.

Need like below screenshot, and i have used dropdown field so that user can select 1 cost type for each row

Please guide me on this, thanks in advance