$Elements$
3
1
5
7
$EndElements$

1 65 71
2 32 87
3 39 98
4 41 63

$Elements$
1 65 71
2 32 87
3 39 98
4 41 63
$EndElements$

lead='^$Elements$$'
tail='^$EndElements$$'
# f2 is the file where the information
# to replace is kept in
sed -e "/$lead/,/$tail/{ /$lead/{p; r insert_file
    >         }; /$tail/p; d }"  f2

echo -e '/$Elements$/+1,/$EndElements$/-1dn.-1r f2nw' | ed -s f1

sed -e "
   /$lead/,/$tail/!b
   //!d
   /$lead/r f2
" f1

$Elements$
1 65 71
2 32 87
3 39 98
4 41 63
$EndElements$