Question GEDCOM import - all data replaced?

When I view the GEDCOM import function, it says:

"This will delete all the genealogy data from ‘Hugh McKenzie Mackay’ and replace it with data from a GEDCOM file."

Is there any way to import new (supplementary) data from a GEDCOM file without the existing data being all deleted?

For example initial GEDCOM file contains one branch of a family.
Then later I have a GEDCOM file containing another branch - is it possible import this and merge it with the original data?
 

Import the GEDCOM file into a second (temporary) tree.

Then use the "Merge trees" option.

Thanks.