A family of Microsoft relational database management systems designed for ease of use.
Irene,
Simple answer is "no", at least if you are referring to the split task function in Project.
Please note that a summary task is not really a task at all despite the name, rather it is a summary of the tasks under it. The start of a summary line is defined by the start of the earliest subtask and the finish of a summary line is defined by the finish of the latest subtask.
You can "split" a summary by breaking the subtasks under it into two separate summary groups. That would effectively "split" a summary task.
Hope this helps.
John