To ensure correct transition from one plan to another, you should always group plans based on their compatibility, so plans with the same settings belong to the same group. Don't group plans of different nature (for example Windows and Linux hosting), as this will lead to unexpected results. A very common mistake is to create dedicated Unix and Win2000 trial plans and put them in a separate trial plans group. On the one hand, this will not allow trial users to switch to pay plans, as they are in a different group. On the other hand, when switching from Win2000 Trial to Unix trial, a user will lose the settings that are unavailable under Unix plan, such as ASP and ODBC service.