Combine book that was published in multiple volumes

[Pedro]

Hello,

I want to combine a portuguese translation of a book by Ben Bova.
But the portuguese version was edited in 2 volumes (books) and the original was just 1.

how should i combine the editions?

thanks
Pedro Pires

[rivka, Former Moderator]

You cannot, unless there is another version also split into two volumes.

[Pedro]

so, what is the best practice in this cases?

[rivka, Former Moderator]

To leave them uncombined.