Need help with an excel formula stumped!

I have an excel file and one part of it is manual with a lot of entries each week. I know this can be done with excel but i am not sure of the formula to get this working.

I have a column called OTC. Basically what this column purpose is to check if a task has a bug with it and this data will then be used in a pivot table. If the task is task underneath then there is no bug and it will return a 0 as in that task had no bugs. If a task has a bug underneath then it will be called a value based on how many child bugs there are. eg. if there is 4 bugs a 4 will go in the parent task.

The bugs will have no data as these are the child bugs from the parent task. This is pulled from Team Foundation Server. Would anyone know the code to do this, it has us all stumped and would save so much time automating it. File is attached!

Cheers
Andrew