How can I reference value of a field from a diffrent line in formatted search

I want to use a formatted search for this

I want to set a field value based on a value from a previous row. ( is this possible at all ?)

I have a udf called Test at Line Level on AR Order

The user enters a value for test on line 1

he will have a lot more lines then after that. all I want is to copy the value in test ( on row 1) to row2 as the user edits say the Item code on that row.