Need some guidance regarding the API calls.
If I create Custom Objects related to the Leads, and invoking the API call to insert multiple leads. How does the API work.
a) Do I need to add first all the leads and then update the custom object
b) Does the API calls do the leads and custom object together and then move to next record
Custom objects and leads have different endpoints, hence the answer is - you'll need to create leads and custom objects separately.
Hope that helps.