Looking around the net it appears that the best place to hook into the Lead Conversion process is in a Trigger's After Update event.

I have a situation where I have a related object on a lead and upon conversion, for those that create a new Contact I want to do one thing, but if it's a merge with an existing contact I want to do another.

My problem is, I can't figure out how to know whether the merge was to an existing contact or new contact.

I would think that ConvertedContactId would give me a value for both new and merge?

```
    if (lead.IsConverted && !trigger.oldmap.get(lead.id).IsConverted) {
        // Handling conversion

        // Step 1 - get all existing Status Trackers for lead, that are not Existing Contacts
        //   and migrate to new Contact id

        // Step 2 - get all existing Status Trackers for lead -- that are for 
        //   existing Contacts and delete them
    }

```