transfer data from main form to tabular subform

[juicybeasty]

I need to write VBA code to transfer information from a main form to one of its subforms if a condition equates to true. I would do this bit with the OnUpdate event of one of the controls in the main form and using If Then Else.
The problem is that the subform is tabular, and I find that anything which is transferred to it appears the same on all lines. I want to keep automatically adding new lines with the information from the main form in which each line in the subform is different.
Is this possible in Access 97?