Problems with serial communication for AccelStepper

[Mattman2197]

#include <AccelStepper.h>
#include <MultiStepper.h>

#define MaxSpeed 3600
#define MaxAcceleration 3600

long int moveTo1;
long positions[6];

char id;
String exe;
int idNum;

String msg = "Please Enter Motor ID Followed By The Rotation Value:";
String msg2 = " Rotating To: ";

AccelStepper stepper1(1, 2, 3);
AccelStepper stepper2(1, 4, 5);
AccelStepper stepper3(1, 6, 7);
AccelStepper stepper4(1, 8, 9);
AccelStepper stepper5(1, 10, 11);
AccelStepper stepper6(1, 12, 13);

MultiStepper steppers;

void setup() {
  Serial.begin(9600);
  Serial.setTimeout(10);

  motor1();
  motor2();
  motor3();
  motor4();
  motor5();
  motor6();

  steppers.addStepper(stepper1);
  steppers.addStepper(stepper2);
  steppers.addStepper(stepper3);
  steppers.addStepper(stepper4);
  steppers.addStepper(stepper5);
  steppers.addStepper(stepper6);
}

void loop() {
  Serial.println(msg);
  while (Serial.available() == 0) {

  }

  while (exe != "exe") {
    idNum = Serial.peek();
    moveTo1 = Serial.parseInt();

    id = idNum;

    Serial.print("Motor: ");
    Serial.print(id);
    Serial.print(msg2);
    Serial.println(moveTo1);
    break;
  }

  exe = Serial.readString();  

  motor1();
  motor2();
  motor3();
  motor4();
  motor5();
  motor6();

  if (exe == "exe") {
    Serial.println("Executing");
    steppers.moveTo(positions);
    steppers.runSpeedToPosition();
  }
}

void motor1() {
  if (idNum == 65) {        //set motor id to A
    positions[0] = moveTo1;
    stepper1.setMaxSpeed(MaxSpeed);
    stepper1.setAcceleration(MaxAcceleration);
  }
}

void motor2() {
  if (idNum == 66) {        //set motor id to B
    positions[1] = moveTo1 / 5;
    stepper2.setMaxSpeed(MaxSpeed / 5);
    stepper2.setAcceleration(MaxAcceleration / 5);
  }
}

void motor3() {
  if (idNum == 67) {        //set motor id to C
    positions[2] = moveTo1 / 5;
    stepper3.setMaxSpeed(MaxSpeed / 5);
    stepper3.setAcceleration(MaxAcceleration / 5);
  }
}

void motor4() {
  if (idNum == 68) {        //set motor id to D
    positions[3] = moveTo1 / 5;
    stepper4.setMaxSpeed(MaxSpeed / 5);
    stepper4.setAcceleration(MaxAcceleration / 5);
  }
}

void motor5() {
  if (idNum == 69) {        //set motor id to E
    positions[4] = moveTo1 / 5;
    stepper5.setMaxSpeed(MaxSpeed / 5);
    stepper5.setAcceleration(MaxAcceleration / 5);
  }
}

void motor6() {
  if (idNum == 70) {        //set motor id to F
    positions[5] = moveTo1 / 5;
    stepper6.setMaxSpeed(MaxSpeed / 5);
    stepper6.setAcceleration(MaxAcceleration / 5);
  }
}

I'm trying to control a series of stepper motors for a project. I'm trying to make it work by having me input a series of instructions (ex. A8000, A being the motor id and 8000 being the amount) and sending them to the Arduino via serial monitor. I want all of the motors to be able to move at the same time if I tell them to, so I setup the run command with a trigger separate from the motor id and rotation value.
Upon testing I managed to get it to work, but only if I set the moveto value before uploading the code. Whenever I try to have both the execution function and the moveto function run at the same time it doesn't work and depending on the order I have them in the code it will either think the "e" in "exe" is a motor id, or it will not understand my motor ids at all. How could I make them work together and not block each other?

Sorry for the rushed text, I'm in a hurry to go somewhere and I wanted to post this before I left.