Starting with the second row, and for each subsequent row, select the entire row, and then in the Text Properties window, check the box "Hide paragraph if formula is true" with the formula:
( ! @IsDocBeingEdited & ThisRowKeyField = "" ) | LastRowKeyField = ""
Substitute the name of a required field in the current row for ThisRowKeyField, and the name of a required field in the previous row for LastRowKeyField. What this will do is suppress the display of any blank rows for read and print, and suppress all blank rows except one in edit mode.
Then you will need a way to "add" rows as they are entered by "un-hiding" them as needed, so put a button or hotspot in the form or on the action bar entitled "Add a row" with the formula:
@if(BottomRowKeyField=""; @Command([RefreshHideFormulas]); @Prompt([OK];"Error";"Thirty rows is maximum"))