I'm adding the leads using the crm api and at the same time I'm creating a record in my custom module. The field that should link them (to avoid duplicates in custom module) is email address. Should I be using email address as the required Untitled Name field when I create the custom module?

Whilst adding the records I'm assigning the returned IDs to variables so that I can use them with the updateRelatedRecords function (as this seems the logical thing to do?)

What I want to see in the crm is in the custom module I should see a list of all leads related to it.

In the Leads module I should see the related custom module record.

First question is what lookup fields should I be adding to custom module/Leads?

How should I be creating that relationship using api functions? I assume updateRelatedRecords but will I need to call that twice? Once for Leads and once for custom module?