If I understand you correctly, this should work:

Code:

sed 's/.*Secondary Ins\..*/&\n1/'

To introduce the new features in our match (search) string:
. is regex for ANY character
* is regex for the previous character can occur any number of times, from 0 on up

Replace string:
& is like a variable, it expands out to the content of whatever your found
\n is a newline

So we're searching for any lines containing "Secondary Ins." (escaped the . so it becomes a literal period, ensuring we won't match, e.g. "Secondary Insurance") and replacing them with themselves (simply put) and then adding a newline and a 1. Good?