I discovered a bug/flow
When my users convert leads, they do not always create an oppty, nor do they want to.
It so happens, that once this oppty is created, if it wasn't created during the conversion, it will NOT relate to the lead-converted report - and will not reflect marketing efforts for leads in income.
What report (or action) can I take to take these scenarios in the reports?
As you've observed, these records won't be attached to leads. A safer bet would be to use Campaigns, which are designed to track ROI on marketing investments. Using the Primary Campaign field on opportunity, the users can choose which marketing effort the opportunity arose from. The only problem now is getting them to change their process. The only change you need to make to leads is to have the users select a campaign when creating the lead (or before conversion, at least). Opportunities not from leads will need to have their campaign manually selected.
You have some marketing information on the LEAD such as "Lead_Source". At conversion an opportunity is NOT created, so this information is not copied to the opportunity.
Map the marketing information, such as "Lead_Source" in lead conversion mapping to be set on a custom field on the account and create a report at the account level. (You will likely need to have some rollup summary fields on the account to count the value or other info from the opportunity.
Create an opportunity trigger that on creation of the opportunity will "find" the original lead (from the Lead.ConvertedAccountID) and either copy the data (lead_source) onto the lead or link the opportunity to the originating lead through a custom lookup field.
I understand where you are as marketing need to measure/claim the source/cost of the lead generation activities. Both of the above options will require new reports, process and an approach to deal with all of your existing leads/opportunities.
I was able to solve this problem for newly converted leads, but unable to alter previously converted leads: On updating an account with a lookup to Lead: Cannot Reference Converted Lead
The solution was to create a field on Account that references the Lead that it was converted from, and populate this with a trigger. This relationship could then be used with a custom report type based on Opportunity that pulls in the Account and Lead fields.
Luckily my customer was happy for this report to only work from deployment into the future as there was no way to create references to the already converted Leads.
You won't get this from a Lead report, since this will only relate to the Account/Contact/Opportunity created during that conversion process and nothing afterwards. You might want to carry over some other values into the Account/Contact to specify
You will need to create an Accounts or Contacts with Opportunities report, though.
What I ended up doing, is create a CB field on an oppty: First Sale
Also: on the account: roll up summary of: closed won opptys.
The First Sale value is set to true - and a workflow + field update set's it to false if the : closed won opptys > 1 when it's created.
