Have been given the requirement to change the Lead Entity so that the Account (companyname) attribute is 'Business Recommended' and it changed to a lookup of accounts rather than the free text field.
I don't see a way to change the attribute type to 'Lookup' and can't remove the attribute to re-add it as a Lookup as I get the message 'System attributes cannot be deleted'.
The reasoning behind this is that we often deal with 'Leads' within an organisation with which we already have contacts (for potentially staff training etc) and want' to accurately link the leads to the organisation. This keeps our Contacts list clean as only people we are actively in a relationship with become contacts.
You can do that by adding a N:1 relationship between the Lead and the Account and exposing the field on the Lead form.
However, consider using the opportunity instead than the lead for what you need to do. You can add a text field with the name of the contact to the Opportunity, and since you are using well formed Leads (i.e. you know who you are dealing with, it's a repeat business etc.) you can just use another opportunity field (pipeline stage / status / whatever you want) to mark the opportunity as a "Lead", so you will be able to distinguish / filter between opportunities that you consider "Leads" and regular opportunity. The advantage is that you can convert a lead to an opportunity by just changing its status.
The idea of Leads is more to enter things like information from a business card of somebody who stopped by at your booth and expressed interest.
But I understand your requirements, just wanted to throw a different way around it.
