My question is based on this article Executing Multiple Instance Activities

I used the second suggested approach (Using a Conditional Start) and I am facing an issue I hope someone could help me solving it. 

I am having multiple instances for the Testing activity, it will be triggered using a condition and it will wait until all the testers finish their testing after that I will move to the next step. my next step is to check if the decision is approved or not, to check this I normally use the Case Services API server action, specifically, I am using the CaseActivityAction_Get method. For using the method I need the activity id of the Testing activity which is not accessible here. I need a way to get the activities ids of the Testing activity (that is inside the conditional start) to be able to get the actions.

Thanks in advance.