sed to read line by line and input into another file

I have two files.

Fileone contains

text string one
text string two
text string three

Filetwo contains

Name:
Address:
Summary:
Name:
Address:
Summary:
Name:
Address:
Summary:

I would like to use sed to read each line of file one and put it at the end of the summary line of file two.
Like this

Name:
Address:
Summary:Text String one
Name:
Address:
Summary:Text string two
Name:
Address:
Summary: Text String three

I have tried several things. But this got close.

while read line;
do
  sed "/Summary/s/$/$line/g" filetwo 
done < fileone

This puts text string one from file one onto each of the Summary lines. I would in fact like to have text string two put on the second Summary field. I though sed should read a file line by line anyway so the while may not be necessary but like I say it got me closest. I also tried placing double quotes around the "$line" this seemed to take each text string properly but gave an error due to incorrect expression. Any help would be appreciated.

Thanks..

#!/bin/bash

exec 3<file1
while read line
do [[ $line == Summary: ]] && {
      read -u 3 toadd
      echo "$line$toadd" >> file3
   } || echo "$line" >> file3
done <file2
mv file3 file1

this also works with ksh93.

Hi

awk 'NR==FNR{a[i++]=$0;next;}{ if ($0 ~ /Summary/) printf"%s %s\n", $0,a[j++];else print;}' i=1 j=1 file1 file2

Guru

Thanks for the replies. I used the awk solution. It was easier to run and quicker as I changed the "Summary" pattern to match several other patterns as well.

Thanks..