I am merging in MS Word from a .dat file. I set

I am merging in MS Word from a .dat file. I set it up as a directory so that the rows of data would merge contiguously instead of each breaking to a new page. I need to format the columns in Title Case, lowercase or Sentence case. The only way I can get it to keep this formating is to have Repeat Header Rows turned on. But then I can't sort the merge file. If I turn Repeat Header Rows off, everything merges in uppercase. I tried putting a header row in, but when I did that, each row of data had a header row attached. How can I get contiguous rows of data with the header only at the top of each page and the fields with the title, sentence or lowercase format I want, with the format retained when the data refreshes? Thank you for your help.