SubForm Problem(Help) i am on the edge

[DD]

I have a Mainform with a subform insereted into it "works well"
I want to place another form but not into the mainform i want to link
of a CmdButton.
When you move from one record to the next IN THE MAINFORM the subform
relates to the mainform via the CustomerID (regardles of a new entry
in the subform or not).
I have tried and tried to get the new form that is linked via the
CmdButton to do the same.
I am ready to throw the computer out the window.
DD