Adding new book or edition?

[THEOENG]

Hello! I'm sorry if this question has been asked before, but I'm a bit confused and need some help.

There is 1 whole book that already has data in goodreads database,
and later this year, they just reprinted this book with new editions that split the same book into 2 books with different ISBN13, which never has in database before.

What should I do next? Adding both 2 books as the new books in series or adding both as a new edition on the same original book? Please advice:) Thank youuu

[Scott]

If the two volumes collectively have a single ISBN, they can be considered a new edition of the previous single volume.

If each volume has its own ISBN, they would have to be added as separate books.