there is no standard / common practice Best practice must be where every party is individually identified each with a clear role and individually accountable. That said there are many cases where the client undertakes all the roles and makes a very good job of it and v versa Look at what is to be undertaken and look at your company competences and if all is OK go the route that looks best for you - Keeping all things in-house / in one place can save £ and ensure adequate control provided people are prepaired and competent to manage properly