Calling function in one form from another

Question

I have a program where Form1 is a MDI parent to form 2. In the menu on Form1, I have an option which creates a dialog (Form3) for the user to enter information and save that information to a file. When the user clicks the button on Form3 to save the information, I would like to be able to do one of two things. Add this information to a List on Form2 or call a function on Form2 to reload all the data from a file. I have not been able to figure out how to do either. Another option I have considered, but do not know how to do is create an event handler which would fire when Form2 regains focus, I have not found an event which I feels works for this, but I am guessing I have just missed it. This option is behind the other options, as I would reload the data more often than should really be required, but would work if the above will not.