Create Node and related Node at the same time?
The Inline Entity Form module will get you that functionality (assuming your reference field is provided by the Entity Reference module).

Provides a widget for inline management (creation, modification, removal) of referenced entities.
The primary use case is the parent -&gt; children one (product display -&gt; products, order -&gt; line items, etc.), where the child entities are never managed outside the parent form.
Existing entities can also be referenced.