diff --git a/test/merge_2_debian_isos b/test/merge_2_debian_isos
new file mode 100755
index 00000000..dd0f9fe0
--- /dev/null
+++ b/test/merge_2_debian_isos
@@ -0,0 +1,357 @@
+#!/bin/bash
+
+usage() {
+  echo "usage: $(basename "$0") "'\' >&2
+  echo "       boot_iso boot_mount add_iso add_mount result_iso [for_dist]" >&2
+  echo >&2
+  echo "Mounts by sudo the boot_iso at directory boot_mount and add_iso at" >&2
+  echo "add_mount, if not already mounted that way. Then both Debian pools" >&2
+  echo "and package lists get merged and a new ISO 9660 image result_iso" >&2
+  echo "is produced, which must not yet exist." >&2
+  echo "If boot_iso is bootable then the new image will be bootable by the" >&2
+  echo "same means." >&2
+  echo "This script creates the following temporary tree and files which" >&2
+  echo "must not yet exist in the current working directory:" >&2
+  echo "  ./merged_dists , ./merged_md5sum.txt , ./merged_REAMDE.txt" >&2
+  echo "  ./temp_file" >&2
+  echo "The optional sixth argument for_dist should only be given if" >&2
+  echo "this script refuses to work and proposes to give this argument." >&2
+  echo "Exported non-empty variable MERGE_DATE enforces a particular" >&2
+  echo "date string in the text which gets prepended to /README.txt ." >&2
+  echo "Exported non-empty variable XORRISO overrides command xorriso," >&2
+  echo "which may be needed if installed xorriso is older than 1.4.2." >&2
+  echo "Example using GNU xorriso-1.5.4 instead of /usr/bin/xorriso:" >&2
+  echo "  export XORRISO="'$HOME'"/xorriso-1.5.4/xorriso/xorriso" >&2
+  echo "  $(basename "$0") debian-11.2.0-amd64-DVD-1.iso /mnt/iso1 "'\' >&2
+  echo "          debian-11.2.0-amd64-DVD-2.iso /mnt/iso2 merged.iso" >&2
+}
+
+if test "$#" -lt 5
+then
+  usage
+  exit 1
+fi
+
+BOOT_ISO="$1"
+BOOT_ISO_MOUNT="$2"
+ADD_ISO="$3"
+ADD_ISO_MOUNT="$4"
+RESULT_ISO="$5"
+
+# The sixth argument is optional
+FOR_DIST="$6"
+
+
+## Check arguments
+
+if test -e "$RESULT_ISO"
+then
+  echo "--- A file '""$RESULT_ISO""' is already existing." >&2
+  echo "--- Will not overwrite it by the resulting ISO image." >&2
+  exit 1
+fi
+if test -e merged_dists || test -e merged_md5sum.txt || test -e temp_file \
+   || test -e merged_README.txt
+then
+  echo "--- At least one of ./merged_dists, ./merged_md5sum.txt, ./temp_file," >&2
+  echo "--- or merged_README.txt is already existing. Will not overwrite them." >&2
+  exit 1
+fi
+if test "$BOOT_ISO" = "$RESULT_ISO" || test "$BOOT_ISO" = "$ADD_ISO" || \
+   test "$ADD_ISO" = "$RESULT_ISO"
+then
+  echo "--- At least two of the three given ISO image paths are equal." >&2
+  echo "--- boot_iso and add_iso must exist and differ, result_iso must not exist." >&2
+  usage
+  exit 1
+fi 
+
+
+## Mount and copy out the files which need to be changed
+
+do_mount_1=1
+x=$(mount | grep " $BOOT_ISO_MOUNT " | awk '{print $1}')
+if test -n "$x"
+then
+  i1=$(ls -i "$x" | awk '{print $1}')
+  i2=$(ls -i "$BOOT_ISO" | awk '{print $1}')
+  if test "$i1" = "$i2"
+  then
+    do_mount_1=0
+    echo "Note: Found $BOOT_ISO already mounted at $BOOT_ISO_MOUNT"
+  fi
+fi
+if test "$do_mount_1" = 1
+then
+  echo "Note: sudo mount $BOOT_ISO $BOOT_ISO_MOUNT"
+  sudo mount "$BOOT_ISO" "$BOOT_ISO_MOUNT" || exit 3
+fi
+cp -a "$BOOT_ISO_MOUNT/dists" merged_dists
+cp -a "$BOOT_ISO_MOUNT/md5sum.txt" merged_md5sum.txt
+chmod -R u+w merged_dists
+chmod u+w merged_md5sum.txt
+
+do_mount_2=1
+x=$(mount | grep " $ADD_ISO_MOUNT " | awk '{print $1}')
+if test -n "$x"
+then
+  i1=$(ls -i "$x" | awk '{print $1}')
+  i2=$(ls -i "$ADD_ISO" | awk '{print $1}')
+  if test "$i1" = "$i2"
+  then
+    do_mount_2=0
+    echo "Note: Found $ADD_ISO already mounted at $ADD_ISO_MOUNT"
+  fi
+fi
+if test "$do_mount_2" = 1
+then
+  echo "Note: sudo mount $ADD_ISO $ADD_ISO_MOUNT"
+  if sudo mount "$ADD_ISO" "$ADD_ISO_MOUNT"
+  then
+    dummy=dummy
+  else
+    if test "$do_mount_1"
+    then
+      sudo umount "$BOOT_ISO_MOUNT"
+    fi
+    exit 3
+  fi
+fi
+
+
+## Helper functions
+
+# Put out the list of checksummed paths as listed in /dists/$dist/Release
+extract_checksum_paths() {
+  mode=0
+  cat "$1" | \
+  while true
+  do
+    read x || break
+    if test "$x" = "MD5Sum:" || test "$x" = "SHA1:" \
+       || test "$x" = "SHA256:" || test "$x" = "SHA512:"
+    then
+      if test "$mode" = 0
+      then
+        mode=1
+      elif test "$mode" = 1
+      then
+  break
+      fi
+    elif test "$mode" = 1
+    then
+      echo "$x"
+    fi
+  done
+}
+
+# Put out the part before the first checksum field
+extract_release_head() {
+  cat "$1" | \
+  while true
+  do
+    read x || break
+    if test "$x" = "MD5Sum:" || test "$x" = "SHA1:" \
+       || test "$x" = "SHA256:" || test "$x" = "SHA512:"
+    then
+  break
+    fi
+    echo "$x"
+  done
+}
+
+
+## Determine which Debian release is on BOOT_ISO
+
+dist=
+for i in $(ls -1d "$BOOT_ISO_MOUNT"/dists/*)
+do
+  if test -d "$i"
+  then
+    if test -L "$i"
+    then
+continue
+    fi
+    test -n "$dist" && dist="$dist "
+    dist="$dist""$(basename $i)"
+  fi
+done
+if test -z "$dist"
+then
+  if test -z "$FOR_DIST"
+  then
+    echo "--- Cannot determine Debian release from directories in /dists" >&2
+    echo "--- (You may provide the release name as sixth argument)" >&2
+    echo >&2
+    usage
+    exit 2
+  fi
+elif test "$(echo "$dist" | wc -w)" -gt 1
+then
+  if test -z "$FOR_DIST"
+  then
+    echo "--- More than one Debian release found in /dists: $dist" >&2
+    echo "--- (You may provide the release name as sixth argument)" >&2
+    echo >&2
+    usage
+    exit 2
+  fi
+fi
+if test -n "$FOR_DIST"
+then
+  echo "Note: Overriding release name '$dist' by '""$FOR_DIST""'" >&2
+  dist="$FOR_DIST"
+fi
+if test -d "$BOOT_ISO_MOUNT"/dists/"$dist"
+then
+  echo "Note: Will work along $BOOT_ISO_MOUNT"/dists/"$dist"/Release >&2
+else
+  echo "--- Cannot find directory $BOOT_ISO_MOUNT"/dists/"$dist" >&2
+  exit 2
+fi
+
+
+## Prepend info to /README.txt
+
+if test -z "$MERGE_DATE"
+then
+  MERGE_DATE=$(date +'%Y%m%d-%H:%M')
+fi
+printf 'Result of a run of %s at %s\r\n' \
+       "$(basename $0)" "$MERGE_DATE" >temp_file
+printf 'Package pools and Packages lists were merged.\r\n' >>temp_file
+printf 'The other files stem from the first input ISO.\r\n' >>temp_file
+printf '\r\n' >>temp_file
+printf 'Input ISO: %s\r\n' "$BOOT_ISO" >>temp_file
+head -2 "$BOOT_ISO_MOUNT"/README.txt >>temp_file
+printf '\r\n' >>temp_file
+printf 'Input ISO: %s\r\n' "$ADD_ISO" >>temp_file
+head -2 "$ADD_ISO_MOUNT"/README.txt >>temp_file
+printf '\r\n' >>temp_file
+printf '%s%s\r\n' " --------------------------------------" \
+                  "----------------------------------------" >>temp_file
+printf '\r\n' >>temp_file
+cat "$BOOT_ISO_MOUNT"/README.txt >>temp_file
+
+mv temp_file merged_README.txt
+
+
+## Merge package description files with those from "$ADD_ISO"
+
+# /md5sum.txt seems to be the only overall package list
+cat merged_md5sum.txt "$ADD_ISO_MOUNT"/md5sum.txt | sort >temp_file
+mv temp_file merged_md5sum.txt
+
+# Determine the files which are mentioned with checksum in main Release files
+path_list=$( (extract_checksum_paths merged_dists/"$dist"/Release
+              extract_checksum_paths "$ADD_ISO_MOUNT"/dists/"$dist"/Release ) \
+             | awk '{print $3}' | sort | uniq )
+
+# Merge .gz files (Release should not be merged. Unclear what others need.)
+for i in $path_list
+do
+  if echo "$i" | grep -v '.gz$' >/dev/null
+  then
+continue
+  fi
+  if test -e merged_dists/"$dist"/"$i"
+  then
+    if test -e "$ADD_ISO_MOUNT"/dists/"$dist"/"$i"
+    then
+      if test "$(gunzip <merged_dists/"$dist"/"$i" | tail -1)" = ""
+      then
+        empty_line=
+      else
+        empty_line=echo
+      fi
+      ( gunzip <merged_dists/"$dist"/"$i"
+        $empty_line
+        gunzip <"$ADD_ISO_MOUNT"/dists/"$dist"/"$i" ) | gzip >temp_file
+      mv temp_file merged_dists/"$dist"/"$i"
+    fi
+  elif test -e "$ADD_ISO_MOUNT"/dists/"$dist"/"$i"
+  then
+    if test -e $(dirname merged_dists/"$dist"/"$i")
+    then
+      dummy=dummy
+    else
+      mkdir -p $(dirname merged_dists/"$dist"/"$i")
+    fi
+    cp "$ADD_ISO_MOUNT"/dists/"$dist"/"$i" merged_dists/"$dist"/"$i"
+  fi
+  test -e temp_file && rm temp_file
+done
+
+
+## Update dists/"$dist"/Release
+
+extract_release_head merged_dists/"$dist"/Release >temp_file
+
+# Re-create  "MD5Sum:", "SHA256:", "SHA512:" sections
+for cmd in md5sum sha1sum sha256sum sha512sum
+do
+  if type "$cmd" >/dev/null
+  then
+    case "$cmd" in
+      md5sum)    echo "MD5Sum:" ;;
+      sha1sum)   echo "SHA1:" ;;
+      sha256sum) echo "SHA256:" ;;
+      sha512sum) echo "SHA512:" ;;
+    esac
+    for i in $path_list
+    do
+      file=merged_dists/"$dist"/"$i"
+      if test -e "$file"
+      then
+        sum=$("$cmd" "$file" | awk '{print $1}')
+        size=$(stat -c '%s' "$file")
+      elif test -e "$file".gz
+      then
+        sum=$(gunzip <"$file".gz | "$cmd" | awk '{print $1}')
+        size=$(gunzip <"$file".gz | wc -c)
+      else
+    continue
+      fi
+      list_path=$(echo "$file" | sed -e 's/^merged_dists\/'"$dist"'\///')
+      printf ' %s %8ld %s\n' "$sum" "$size" "$list_path" 
+    done 
+  fi
+done >>temp_file
+
+mv temp_file merged_dists/"$dist"/Release
+
+
+## Produce the new ISO image
+
+if test -z "$XORRISO"
+then
+  XORRISO=xorriso
+fi
+
+"$XORRISO" \
+  -indev "$BOOT_ISO" \
+  -outdev "$RESULT_ISO" \
+  -map "$ADD_ISO_MOUNT"/pool /pool \
+  -map merged_dists /dists \
+  -map merged_md5sum.txt /md5sum.txt \
+  -map merged_README.txt /README.txt \
+  -chown_r 0 /dists /md5sum.txt /README.txt -- \
+  -chgrp_r 0 /dists /md5sum.txt /README.txt -- \
+  -chmod_r a-w /dists /md5sum.txt -- \
+  -chmod_r a=r /README.txt -- \
+  -boot_image any replay \
+  -stdio_sync off \
+  -padding included \
+  -compliance no_emul_toc
+
+if test "$do_mount_1" = 1
+then
+  sudo umount "$BOOT_ISO_MOUNT"
+fi
+if test "$do_mount_2" = 1
+then
+  sudo umount "$ADD_ISO_MOUNT"
+fi
+
+rm -r merged_dists merged_md5sum.txt merged_README.txt
+