Prevent SoftwareSerial from using PCINT2_vect

Hi everyone,
I have a project in which I need to use SoftwareSerial on pins 11-14 and pin change interrupts on pins A8-A13. The codes I wrote work separately, but when I put them together, I got a compiler error stating that __vector_11 had multiple definitions. After some research, I found on this page SDI-12 and SoftwareSerial Compatibility Issues · Issue #8 · EnviroDIY/Arduino-SDI-12 · GitHub that SoftwareSerial tries to create an ISR for all possible pin change interrupts, but I need it only for pins 11-14.
the solution they gave there was to modify the code of SoftwareSerial to comment out the lines for the wanted vector, but I cannot seem to find the SoftwareSerial files in my libraries, so I would like to know if there is a way to solve this problem. Thanks in advance!

Here is the relevant portion of code in the provided link:

#if defined(PCINT0_vect)
ISR(PCINT0_vect)
{
  SoftwareSerial::handle_interrupt();
}
#endif

#if defined(PCINT1_vect)
ISR(PCINT1_vect)
{
  SoftwareSerial::handle_interrupt();
}
#endif

#if defined(PCINT2_vect)
ISR(PCINT2_vect)
{
  SoftwareSerial::handle_interrupt();
}
#endif

#if defined(PCINT3_vect)
ISR(PCINT3_vect)
{
  SoftwareSerial::handle_interrupt();
}
#endif

You might find more luck with the altsoftserial.h library.

Either way, you can do a quick file search on your machine to find the softwareserial.h library. Just search "softwareserial.h" in either Finder (for mac) or File Explorer (for PC). Trust me, it's on your machine.

Thank you for the reply. I have searched the whole computer for SoftwareSerial.h with no luck. the other libraries are all in the usual libraries folder. I can't understand how the IDE is able to use them.
As for AltSoftSerial, I would prefer making the code work with SoftwareSerial because there will be a lot to modify, but thanks for the suggestion.
EDIT: I found it and modified the code. Now it compiles fine. thank you a lot!