Add items to list

Question

Currently I'm creating a list in "Form1" pretty much this:

        //
        //
            this.Shortlist = new System.Collections.Generic.List<Shortlist>();

            this.ShortlistIndex = (int)binaryReader.BaseStream.Position;

            for (i = 0; i < (int)shortlistnum; i++)

            {

                Shortlist item2 = new Shortlist(binaryReader);

                this.Shortlist.Add(item2);

            }

            binaryReader.Close();

The Shortlist class is:

    public class Shortlist

    {

        public string Name;

        public string Nation;

        public string NationalityName;

        public int Age;

       

        public Shortlist()

        {

        }

        public Shortlist(System.IO.BinaryReader reader)

        {

            this.Name = reader.ReadString(128).Replace("\0", string.Empty);

        }

    }

All works fine..I then call another function (still in Form1) which joins this list with another list to create a 3rd list (and bind it to a listview):

        private void Populate(object sender, EventArgs e)

        {

            var userlist = (from Item1 in Shortlist

                              join Item2 in People

                              on Item1.Name equals Item2.FullName

                              into grouping

                              from Item2 in grouping.DefaultIfEmpty()

                              select new

                              {Item2.FullName

                               ,Item2.Age

                               ,Item2.CountryName

                               ,Item2.Nationality

                              }).ToList();

            this.fastObjectListView3.SetObjects(userlist);

        }

Again, happy with this, all is ok..

In "Form2" I have a button and when clicked I want to pass a pre-defined string/item/value/object...whatever you call it and  add it into this.Shortlist (In Form1) and then my "Populate" function called to repopulate & bind my 3rd list.

I can't seem to work out how to add across classes..any help..Vulpes :p would be great