asterisk users - Jan 2018 - Can anyone help with a quick app_record.c module improvement and can explain over-riding modules?

Hello,

I want to start recording with a prompt of "press or say 1 to 5". If
no DMTF is pressed, I want to send the recording to Google Speech to
get the number back (got that part working already).

If any dtmf key is pressed while Application_Record  is running with
option y, then the recording terminates and sends
RECORD_STATUS of "DTMF" (A terminating DTMF was received).

But I need to know **what** number that DTMF was, and I can't see a
way of grabbing it after the fact.

I can see in the code where the right variables are..

https://github.com/asterisk/asterisk/blob/master/apps/app_record.c#L140
dtmf_response

https://github.com/asterisk/asterisk/blob/master/apps/app_record.c#L166
* \param dtmf_integer the integer value of the DTMF key received

So,3 questions I guess:

1: Am I going about this the right way? (unimrcp is not an option here)
2: Can someone explain in layman's terms how a simpleton like me could
copy, hack about with and make a new module, like, for example,
app_record_alt.c, that would stick around each time I updated Asterisk
from source?
3: Or, is anyone willing to make the simple code change to the file to
improve it to send back the DTMF to the dialplan? For free to improve
core code? If not, and I posted on the commercial list, how much would
I be looking at to modify about 6 lines of code and return an extra
variable?

So, ultimately, I'm hoping for something like:

Currently:
option "y" returns a RECORD_STATUS of "DTMF" if a key was
press

Hopefully:
option "z" returns a RECORD_STATUS of <dtmf-value> showing which
key
was pressed.
Or possibly even DTMF_VALUE (if an app can return two variables to the
dialplan?)

I'm sure this would benefit a lot of people.

I posted this a few days ago in the forum at
https://community.asterisk.org/t/can-anyone-help-with-a-quick-app-record-c-module-improvement-and-can-explain-over-riding-modules/73221
but no-one bit, so, I'm hoping this list can help.

Many thanks!