Insert Records in multiple Objects in single DML
There could be many cases where you need to insert records in multiple objects in a single method but you might end up with TOO MANY DMLs Error.
Here we’ll discuss how you can insert records in multiple objects in a single dml call.
Let’s assume you need to add records in Account, Contact and AccountContact (Custom Object). By using the below code, you add records in all 3 objects in a single DML call.
Source : https://salesforce.stackexchange.com/questions/141897/insert-multiple-sobjects-in-single-dml-call