A process I've used successfully is to pass to the modal form an object reference of the calling form:

Do Form "YourModalFOrm" With this

Create a property on the modal form to store the reference. I use "oCaller." Then in the init of the form I have code like this:

Init
Lparameters oCallerRef
this.oCaller = oCallerRef

Then in the click method of the button that closes the form you can set the properties and the calling form's controls will be visible:

thisForm.oCaller.Text1.Value = thisForm.StartDate.Value
Etc.