You can't choose which lines to update, but there is a change you could make to your CSV to speed things up. Just find all the places you want those line breaks in the CSV, and put in some placeholder character that doesn't appear elsewhere in the document. ( §, for example ) Then, after the new merge, you just have to globally find the § and replace with a line break.
Thanks SRiegel, that could work. Would still be really tedious to set up all those characters in the 300+ line items in the live, CSV file I'm working out of with the rest of the team. Looks like it's six in one and half dozen in the other
Another option might be the "Find Change by List" script. Build a list of your brand names with a Change to field that includes the line break, then run the script after each new merge.
I've never used this, so I can't swear that it would work, but it seems like a good option.
I don't know if the find/change file can contain line breaks and still work -- if it can't, you could use the special character in the find/change, and then run a second change to get the line breaks in.
Thanks for the suggestions! Seems like most of my options would still involve some tedious things as a work around. I'll keep playing around and see what works the best for us.
If anyone else has any suggestions, I'm happy to hear them too.
Another potential solution occurred to me this morning. Try adding the Balance Ragged Lines attribute to the paragraph style for the product name. That would fix your given example, and it will probably help with at least most of them.
At least from your example, there is a manufacturer name (Nature Valley) and a product name (Protein Cereal). Regardless of the terms, if the breaks will always be like this example, I would make the Excel spreadsheet to hold these values in separate cells.
If that is not possible (for instance, you do not have control of the data or the people supplying the Excel spreadsheet will not themselves separate the data), I would take the time to flesh out a copy of the find/change script mentioned previously for this repetitive task. Once it is done, all you need to do is to add any new info as it becomes available and run the script.