Practice purchase and recent incorporation

I'm looking at buying in as a 50% shareholder with a sole practitioner who incorporated a few years ago. I am considering the aspect of the goodwill that was generated and how this should be dealt with. The sole practitioner has a considerable directors' loan account roughly equal to the goodwill (being amortised over 10 years).

On the most basic level, as the goodwill has not yet been fully written off, this will reduce future profits available to me. Is there a generally accepted method to account for the goodwill within the accounts/directors' loan(s) when purchasing shares in this scenario?

Many thanks

James