The easiest way to do this is to use multiple sections. So, for example, if the "can grow" field is in the Details A section, add a Details B section and put any fields below the can grow field into Details B. Make the can grow field appear as only one line in the design (it will automatically grow to more if necessary) and put the bottom of Details A at the bottom of the can grow field. The section will automatically expand if needed so that the can grow field doesn't overwrite the data below it.
-Dell