How to merge the existing term to entries automatically when import a XML format file based on the sdl multiterm?

Hi everybody

I know when i add terms in sdl multiterm as well as the new term i've entered was already exists, it will prompts me if I need to merge the entries. but if i want to

update a termbase with importing a xml format file based on the sdl multiterm termbase  which may contains some existing terms which i do not hope to add all of

them as new entries, how can i do to merge them to entries automatically?

thanks,

bradley