Converting Leads with Custom Module lookups

Converting Leads with Custom Module lookups

We are a real estate company, so many of our leads use custom modules for commercial properties and residential properties that the leads own. Leads might own one or more properties, so by creating a custom module we have been able to create this connection using a look-up on the custom module. An issue has arose that when we convert the lead we are unable to transfer the custom module's information to the contact/account. Any ideas of how we can transfer this information along?