Prevent Quote Task Tree from Resetting with Customer Change

We developed a lead workflow using CRM tasks and task sets in quote entry. In order to get leads out to our Salesforce quickly we do a simple contact match search with matching emails and if no match is found create a lead under a single generic customer using memos to communicate the customer, contact, and other qualifiers from the lead source. As sales investigates and qualifies the lead they then determine the right customer and contact to use either existing in the DB or creating new and sometimes after completing a few tasks setup by the given lead workflow task set. When changing customers however, the task tree gets reset with all tasks in the quotes task set. Any ideas on how to prevent the task tree from resetting on a customer change?