Jordi,
You should also look at reports that the current parent company has which might be specific to them and might be needed by you also. This would mean rolling out reports - for instance - your parent company might have a sales report tailored for them which might be restricted using values specific for them in the report. This report might not work for you when you roll out the report. You would instead have to create a copy of this report and have it changed for your company.
This would make the roll out more effective because the users will have reports available for them which they can ask users at the parent company for an explanation on how it works etc...