Using parameters on non-mandatory fields

Hello,

I'm using TC 12.53.

I want to use parameters to fill out a applicationform. The're non-mandatory fields which aren't always filled by a parameters. I was expecting that when a parameter is empty the row will still exists in my parameterlist.

For example
1. A.
2. B
3.
4. A

TC updates my rows to:
1. A.
2. B
3. A


How can I fix this?
In the older version of Loadrunner all the parameters were in one row and in one file. I didn't have the problem with empty values in de parameters. In 12.53 each parameter has it's own file with multiple rows, but I can't leave a row empty.

Please help!