How to call 2 windows forms in each other in C++? - winforms

Question

I've been trying to convert a C# program with multiple forms to C++, but turned out that if I just include them in each other, the code would not compile.
I have tried to use forward declarations, but it only gave me issues with object creation.
I also tried to use #indef, but the program still doesn't compile and gives the same errors (c2065, c2061, and c2227 as result when I try to Show() a newly created form).
And I couldn't properly work with ParentForm due to the lack of brains (sadly, but true).
Here is a small part of the code that causes issues for me:
NewPasswordInput.h
#pragma once
#include "Encrypt.h" //class with functions
#include "AccessGranted.h"
namespace PassEncryptPlus {
//...
public ref class NewPassInput : public System::Windows::Forms::Form
{
private: String^ key;
public:
NewPassInput(String^ key)
{
InitializeComponent();
this->key = key;
}
//...
private: Encrypt *encrypt = new Encrypt();
private: System::Void button1_Click(System::Object^ sender, System::EventArgs^ e) {
//...
String^ newpass1 = textBox1->Text;
String^ str = encrypt->WritePass(newpass1); //generating a new key
int i = Application::OpenForms->Count;
AccessGranted^ accessGranted = new AccessGranted(str) //passing the key
accessGranted->Show();
Hide();
}
}
AccessGranted.h
#pragma once
#include "AccessGranted.h"
namespace PassEncryptPlus {
//...
public ref class AccessGranted : public System::Windows::Forms::Form
{
private: String^ key;
public:
AccessGranted(String^ key)
{
InitializeComponent();
this->key = key;
richTextBox1->Text = key;
}
//...
private: System::Void linkLabel1_LinkClicked(System::Object^ sender, System::Windows::Forms::LinkLabelLinkClickedEventArgs^ e) {
NewPassInput^ newPassInput = gcnew NewPassInput(str);
newPassInput->Show();
Hide();
}
}
Thank you in advance!
PS: AccessGranted appears first called by the form I didn't list here, if the order is important.