C# call CRUD functions on another form

See more:

C#

I am trying to put all my CRUD function on one form.
The form works to create the DB and a Table no issues.
So I decided to move the readFriendsData function to the same form.
This form is named frmMakeDB.Then make the CALL from frmSelect which
populates a DataGridView which is not bound to the DB.
I know the DB has one record & the readFriendsData code works if it is
on the frmSelect.
With my limited testing I do not believe any data is being returned ?
I am using C# 7.3 and NetFrameWork 4.8 VS 2019 I have looked at this a lot.
How to call a method from another form[^]
I am NO Pro but The Tuple code look like spaghetti or an after thought !

What I have tried:

Form Select where the method is called and used when returned

private void frmSelect_Load(object sender, EventArgs e)
{
    styleDGV();
    //using (frmMakeDB frm = new frmMakeDB())
    frmMakeDB.readFriendsData();//frmMakeDB.gv_parentInt,frmMakeDB.gv_firstName,frmMakeDB.gv_lastName

    dgvPerson.Rows.Add(frmMakeDB.gv_parentInt, frmMakeDB.gv_firstName, frmMakeDB.gv_lastName);

This is frmMakeDB where the variables are declared as public static strings

    public static string readFriendsData()//string gv_parentInt,string gv_firstName,string gv_lastName
    {
        using (SQLiteConnection conn = new SQLiteConnection($"Data Source = '{"Contacts.db"}';Version=3;"))
        {
            conn.Open();
            using (SQLiteCommand cmd = new SQLiteCommand($"SELECT * FROM FriendsData", conn))
            {
                using (var rdr = cmd.ExecuteReader())
                {
                    while (rdr.Read())
                    {
                        gv_parentInt = rdr["FID"].ToString().Trim();
                        gv_firstName = rdr["fxFirstName"].ToString().Trim();
                        gv_lastName = rdr["fxLastName"].ToString().Trim();
                        //dgvPerson.Rows.Add(gv_parentInt, gv_firstName, gv_lastName);
                    }

                    rdr.Close();
                }
            }
        }

        return Tuple<string, string, string>(gv_parentInt, gv_firstName, gv_lastName);
        //return (gv_parentInt, gv_firstName,gv_lastName);
    }

public static T3 Tuple<T1, T2, T3>(T3 gv_parentInt, T3 gv_firstName, T3 gv_lastName)
{
    throw new NotImplementedException();
}