I have used separate tables in the format for dual line text. Since you cannot segregate the text in parameters as to what belongs on line 1 and what belongs on line 2, I give the option at the relations level. Either enter oneline_description or description_1 and description_2. This way you can have the oneline_description centered or a two line description without regard to the length of the 1st line (to force wrap). IIRC, you also have trouble forcing a wrap -if- the variable for the format table is not long but your assigned value is. The wrap is ignored for the actual entered text. This may have been corrected, but be aware of this possibility.
I also have to do this often with material or finish callouts. Most times they take up only 1 line, but sometimes they require modifiers below.
With established clients, I make the formats with relation driven data entry. I really do not like entering data manually in the format because it is too easy to overlook. Of course, this can get really involved.