SOLVED - New SERCOM interface and how to force SPI devices use it

Greetings everybody. I am building a small project around a custom made SAMD21G board that doesn't use the standard SPI pins (they're not even soldered...) . I can define a new SPI interface using SERCOM5 on pins 11, 12, 13 (using Adafruit's guide) because I want to use an ILI9341 display that I have laying around. The problem is how to force a library that uses SPI to talk to the display, use my own defined mySPI interface.

#include "SPI.h"
#include "wiring_private.h" // pinPeripheral() function
SPIClass mySPI (&sercom1, 12, 13, 11, SPI_PAD_0_SCK_1, SERCOM_RX_PAD_3);

#include "Adafruit_GFX.h"
#include "Adafruit_ILI9341.h"

// For the Adafruit shield, these are the default.
#define TFT_DC 9
#define TFT_CS 10

Adafruit_ILI9341 tft = Adafruit_ILI9341(TFT_CS, TFT_DC);

void setup() {
  mySPI.begin();

  // Assign pins 11, 12, 13 to SERCOM functionality
  pinPeripheral(11, PIO_SERCOM);
  pinPeripheral(12, PIO_SERCOM);
  pinPeripheral(13, PIO_SERCOM);
  tft.begin();
}

As you can see, I instantiated mySPI but I assume that tft.begin() uses the default SPI ports (which as I said, in my case are not even soldered). Is it possible to pass mySPI as a parameter to tft.begin()? Any other thoughts?

Thanks a lot.

EDIT: I solved it. I had to instantiate my tft object with my new defined mySPI interface as a parameter.
The right code is:

Adafruit_ILI9341 tft = Adafruit_ILI9341(&mySPI, TFT_DC, TFT_CS, RST);