First thing to understand is: there is not
functional relationship parent/child between forms. Please see my past answer:
Parent Child Form Relationship[
^]. Even though a form is a
Control with this relationship, it is made defunct for forms.
Now, the main form is a special one: it is defined by the instance passed to
Application.Run. If you close a main form, the whole application (but not the application process) will exit.
Your request is a sing of a flaw in the whole application design. However, there are some cases where the effect you want might be needed.
So, there are at least two approaches.
First, most simple and reasonable is this one: never close the main form but make it hidden instead. This is quite simple.
Another approach is running the singleton
Application twice or more than two times: first with one instance of the form, another time with another one, etc. Look at your method
Main and modify it according to your logic.
For example, please see a code sample I provided in response to a similar question:
Windows Form application[
^].
—SA
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