I have a model where I have two entities. site and owner. relationship between two is the owner has sites. so one owner can have multiple sites. I have a requirement to create owner when i create site. is it possible to use createOwner collection inside the collection step of the stepper of site entity? because when I try to add the collection step inside the site's entity, I can see all the references which are referenced by site entity except owner.

Is there any other way to author the owner inside the site stepper?

It is not possible to create a new reference (Owner) while you are editing or creating a child record (Site).

You will have to create the parent Owner record first, which you can then reference when creating your Site record.

What you can do is the other way around: the AuthorOwners stepper can have a Site Child Collection Step: when you create an Owner, you can optionally create one or more Sites.