Issues with lead conversion

Issues with lead conversion

We are a B2B and have both resellers and repeat business. We currently use the 'Lead' section to track people/companies which come into the business which have yet to be qualified. These 'leads' can be assigned to either a member of our sales team or a reseller depending on the type of business it is. 

There are a number of scenarios where 'leads' are causing an issue because when they are converted into a potential they are automatically creating a new account. This affects both repeat business and resellers within the CRM because both are already listed as accounts.

Ideally I would like to create a lead, convert it into a potential with the option of creating a new account or assigning it to an existing account. Or is it possible to create leads within the account?

Is this possible? Or is there a better way?

Thanks,

Rob.