How to add datas to gridveiw which all ready have datas

Question

I have gridview which already have data

namely...

S.No:   Leave Date Day

1 12/12/2012 Monday

2 13/12/2012 Tuesday

3 14/12/2012 Wednesday

Then i have two textboxes which contain  "Special Holiday date" and "Remarks" 

eg : 16/08/2013 

Remarks : Onam

i want to add it to gridview with out post it in to db.