[Q] WiFi Direct

I have a Nexus 7 2013 "4.3" JSS15R that will be used for data logging of a Bluetooth signal ( A dynomometer on a minature ride on railway ), it will be connected to a backup battery all day and be running at full brightness . The observers are not used to tablets and are only required to touch the "MENU" key at the end of the run and touch "SAVE" then "CLEAR" for the start of the next run . There is no practical phisical way to get the information from the tablet as it will be moving between runs ( uncoupling and coupling up) . The apps I have seen are all send to and I need get from , I have a second Nexus 7 2012 "4.2.2" JDQ39 , I wish to use this to read the files on the on the Nexus used as data logger with WiFi direct , both devices are rooted and I am happy to alter the OS to allow me to read files from one divice to the other , It has to be controlled compleatly from the Nexus 2012 without any requirement to touch the tablet used as the data logger . I need clear instructions on how to get into the OS and what to alter . I found a thread by "18 neverwal previously on the code needed to alter but not on how to get at it . This is the relavent part of his post
The popup dialog that asks for the user to accept/reject a WiFi Direct connection is stored in "<aosp source>/frameworks/base/wifi/java/android/net/wifi/p2p/WifiP2pService.java"
Find the function called "private void notifyInvitationReceived()". Modify it to look like this,
private void notifyInvitationReceived() {
/* comment away all existing code */
/* The following line is added to auto-accept any connections */
sendMessage(PEER_CONNECTION_USER_ACCEPT);
}
Recompile AOSP with this modification and flash your device.