What degree of joint planning and feedback can I expect

Many clients have  senior people in charge of Marketing, Brand, PR and Products etc who naturally wont be happy if they are not playing  a large part in the strategy and the plan.  Furthermore, while a consultant fresh into any business has certain advantages in terms of clarity of vision, it takes years to really understand a product and its users and stakeholders. For these reasons we are keen to discuss this as a first order of business and agree the ideal level of consultation and sign-offs  so everyone is engaged and involved and we can arrive at the best possible outcomes.