Identify rows containing no data in order to 'import' data to main spreadsheet

Hello,

This is my first post so apologies if I make a complete hash. I'm working on a large spreadsheet 14,000+ rows and have just discovered the original CSV that I was sent had some formatting errors and when converting columns to text some chunks of data were left out. Having already done quite a bit of work on the main spreadsheet, cleansing data etc I need to add in the missing data from the original CSV. The additional data only occupies a small proportion of the rows and I need to find a way to either eliminate the blank rows or join it in in some clever manner. I've spent a while scouring the internet but have found nothing that fits the bill as I need to maintain the 'index' column so I can join the right extra bits to the original I've been working on.

I hope this somehow makes some sort of sense to someone!