Wow, some guys never miss the opportunity to SELL! SELL! SELL! (even when it isn’t the solution)
Here’s my suggestion - your .csv needs to conform to what Shopify expects. The easiest way is to get a blank one:
- Create your product(s)
- Select your product(s) and export the them to a .csv
- Fill in the blanks for the images you want (see attached .csv) - Image Src & Image Position are the most important in your case
- I just used Handle in my example, so make sure the Handle is filled in for each row of Image Src & Image Position. You can experiment using some other identifier
- Import that .csv back into Shopify, decide if you want to overwrite, etc.
The attached .csv pulls in 9 images, you can probably get more.