William: Hi WIlliam, the first application I had in mind is to make an 'Invoice required' subtask be dependent on the subtask related to a particular product's completion. For example, we have a main task for each client we service. For each client we may produce multiple products over the course of the year so we create subtasks for each produce or service required, each with the relevant due date. Some products are individually invoiced on completion through out the year. It would be great to be able to make an 'Invoice required' subtask be dependent on a particular product's completion so that our accounts department would not have to check that the product had been delivered before raising the invoice, they would be able to see quite easily when the dependency (visible in the task window) was completed.