Before et Update

Experts,

I have a scenario like below

1. In update mode, i want to fetch values for specific cells from matrix from several rows , means no. of rows added in update.

How to do same?

I have created one field in matrix namely "LineStatus" , once rows are added that shows "closed", next time

when i will again open the form and do "Add Row", it should not consider those "closed" cell values.

How to accompolish same?