Michael,
In addition to Barbara:
If You call the form In method, something like:

*** Some method
LOCAL oForm
DO FORM MyForm NAME oForm LINKED

The oForm variable is declared as LOCAL (If You not declare it the variable is PRIVATE) & after quit of method this form will be released. There is two ways to keep out of this, add a property to main form or declare oForm as a PUBLIC. I prefer first way, because after releaseinf the main form child form release too.