We started using MS Projects recently in our small consulting firm, and one of the types of projects we have are retainer(SLA) based, where the client has a contract for a certain amount of hours per month. Now my question relates to creating tasks on a Project we created for this client, what we are currently doing is we create a main task for each month and assign the amount of hours to that tasks, and then we create sub tasks on that, one for general development and one for business intelligence, what we want to do is share the 150 hours between the two tasks without having to specify the amount of hours for each, as we don't know before hand how they will be split for any particular month.

Currently the main task has 150 hours and both the two sub-tasks on that main task has no hours allocated towards it, each with its own resource assigned to a task.

But when I open PWA and view the projects it says 300 hours has been allocated towards this project.

So what would the best practice be for something like this? And if you have some sources on the internet of where to find more information for something like this, please let me know?

Thanks