What's the best way to export/create multiple documents from VisualBasic to LibreOffice Calc without get the 'Application Is Busy' Error?

I’m looked in the site and foruns, and find a way to export from a FlexGrid to a LibreOffice Calc that appear on the user’s screen so it can save .xlsx.

But when the user tries to open some of his other documents nothing appears, after close the Sheet exported all the documents open at the same time.

Also when the FlexGrid was exported it can’t export another sheet, only if it is closed.