Do you guys think that Natsu is the only demon Zeref created or do you think the other dragon slayers were created by him to?

In the latest chapter it was confirmed that Zeref created/resurrected Natsu and its confirmed they were brothers.Do you think its just Natsu whos related or is there a possibility the other Dragon slayers e.g Wendy and Gajeel are related/created by zeref considering Natsu says he remembers Wendy from somewhere when they first meet?