Ember-Data: Intended usage pattern of DS.EmbeddedRecordsMixin

I've got a backend, that let's me read data asynchronously, but enforces embedding of certain child data (in lieu of transactions).

When using DS.EmbeddedRecordsMixin with ...

{
  serialize: 'records',
  deserialize: 'ids'
}

... (which should be the right thing to do given this backend) I've still got two questions.

(1) http://ift.tt/1orgoFK is very explicit, that DS.EmbeddedRecordsMixin shouldn't be mixed with async:true. From what I understand, the problem would be mixing async:true with embedded reading, not writing. On the other hand the documentation doesn't differentiate. Am I good with mixing async:true with above configuration (and is the documantion missing this case), or what is it that I am missing about async:true and writing?

(2) In my backend when deleting the parent, all children are delete as well. Deleting should be just one call for the parent. How do I do this on the ember end? I want to delete the parent and all children in the store, send one REST request and the success/failure of this request should be authoritative for all those records. Yet, the DS.EmbeddedRecordsMixin doesn't seem to help me in any way in that direction. Am I on my own, or what am I missing?