When I need to add a bunch of "the same" stuff to a FGT I will usually
- get a backup configuration
- copy the respective section out of it
- use some advanced search and replace editor, "Notepad++" or "sublime" do it well as example
- get my to be inserted data set into some format that can then be used to search and replace the unneeded content with the
and so on.
Search your list of IPs for the pattern as text before and after the IP, make it replaceable with some FGT syntax.