IMO you are on a wrong way.
what you are searching is how to send many times the same format of data.
the answer is : after having fulled your fields, send the okcode for adding a new line. (I hope FF67 have one, I’m not at office).
the last time I have used this technique, I have see the last keyed data pushed to line 1.
So I always sent my data into line 2.