Do not combine with the 2018 edition of the same title and ISBN; this edition has at least twice as many pages, half of the articles were written since the 2018 edition was published.
It should be noted that you are supposed to obtain a new ISBN prior to publishing a work that differs from the previous edition to the extent that this one does. If it differs at all, actually; a different cover would suffice. Same cover, but twice as many words...it's not the same work.