my script:

 
FILE="$1"
echo "You Entered $FILE"
if [ -f $FILE ]; then
tmp=$(cat $FILE | sed '/./!d' | sed -n '/regex/,/regex/{/regex/d;p}'| sed -n '/---/,+2!p' | sed -n '/#/!p' | sed 's/^[\
]*//' | sed -e\
s/[^:]*:// | sed -n '/==> /!p' | sed -n '/--> /!p' | sed -n '/regex/,+1!p' | sed -n '/======/!p' | sed -n '/regex/!p' | sed -n '\
/regex/!p' | sed -n '/regex /!p')
fi
MyVar=$(echo $tmp > my.txt)
FILE2="$2"
if [ -f $FILE2 ]; then
tmp2=$(cat $FILE2 | sed -n '/regex/,/regex/{/regex/d;p}' | sed -n '/#/!p' | sed -e s/[^:]*:// | sed /--------/,+10d)
fi
echo "You Entered $FILE2"
MyVar2=$(echo $tmp2 > my2.txt)
var=$(echo hi2.txt | sed '/^$/p' )
echo "$var"
cmp -b my.txt my2.txt

Hi,

it is hard to understand your many sed commands. Perhaps you can
give us an example of what you have and what you want to achieve.

If would combine your first sed-command to delete all blank lines
and double-space the rest at the same time.

sed '/./!d;/./{G}' test