Append text line after multiline match and stop on first multiline match - awk

Question

I would need a sed or awk command, not script, that:
1) matches in file sequentially 2 strings:
# This configuration option has an automatic default value.
# filter = [ "a|.*/|" ]
This is required because any single string can occur in file more than once.
But two of such sequential strings are pretty unique to match them.
2) inserts/appends after matched strings this text line:
filter = ["a|sd.*|", "a|drbd.*|", "r|.*|"]
3) stops processing after first match and append
So, text file looks like this:
...
# filter = [ "a|^/dev/hda8$|", "r|.*/|" ]
#
# This configuration option has an automatic default value.
# filter = [ "a|.*/|" ]
# Configuration option devices/global_filter.
# Limit the block devices that are used by LVM system components.
# Because devices/filter may be overridden from the command line, it is
# not suitable for system-wide device filtering, e.g. udev and lvmetad.
# Use global_filter to hide devices from these LVM system components.
# The syntax is the same as devices/filter. Devices rejected by
# global_filter are not opened by LVM.
# This configuration option has an automatic default value.
# global_filter = [ "a|.*/|" ]
# Configuration option devices/types.
# List of additional acceptable block device types.
# These are of device type names from /proc/devices, followed by the
...
I would need to have output like this:
...
# filter = [ "a|^/dev/hda8$|", "r|.*/|" ]
#
# This configuration option has an automatic default value.
# filter = [ "a|.*/|" ]
filter = ["a|sd.*|", "a|drbd.*|", "r|.*|"]
# Configuration option devices/global_filter.
# Limit the block devices that are used by LVM system components.
# Because devices/filter may be overridden from the command line, it is
# not suitable for system-wide device filtering, e.g. udev and lvmetad.
# Use global_filter to hide devices from these LVM system components.
# The syntax is the same as devices/filter. Devices rejected by
# global_filter are not opened by LVM.
# This configuration option has an automatic default value.
# global_filter = [ "a|.*/|" ]
# Configuration option devices/types.
# List of additional acceptable block device types.
# These are of device type names from /proc/devices, followed by the
...
None of found examples on multiline sed examples on stackoverflow is working for me.
I tried F. Hauri example from this topic: Append a string after a multiple line match in bash
sed -e $'/^admin:/,/^$/{/users:/a\ NewUser\n}'
It works fine, when matching unique words, but did not work for matching sequential text lines like this:
# This configuration option has an automatic default value.
# filter = [ "a|.*/|" ]
and also adding '0, to sed expression to stop on first match did not work in that case.
Updated description to better describe what is the goal.

Answer 1

awk '
/^\s+\# This configuration option has an automatic default value\./{
found=1
}
found && !flag && /\s+\# filter = \[ \"a\|\.\*\/\|\" \]/{
flag=1
$0=$0 ORS ORS " filter = [\"a|sd.*|\", \"a|drbd.*|\", \"r|.*|\"]"
}
1
' test.conf > test.tmp && cp test.conf test.conf.bak && mv -f test.tmp test.conf