4. The method of claim 2 , further comprising: receiving a second input to the first computer system instructing the processor to perform a modification on the received additional activity data item; and transmitting the modification from the first computer system to the second computer system.
2. The method of claim 1 , further comprising receiving an input instructing the processor to associate the received additional activity data item with the hierarchical data structure as a child or parent of one of the activity data items of the hierarchical data structure.