Dear Engineer Heba,
Following are the recommended sequence:
1- Add the Event to the Baseline program and perform as planned analysis, we call this one W0 (Let us say that the delays are 30 days).
2- Find the nearest update to the event finish date just before the impact of the event finished, we call this W1
3- Update W1 with the impact of the event and we call this W2.
Now, if W1 finish date is later than W0, it mean these delays are from contractor since the project was delayed more than the event impact (i.e in our case more than 30 days).
If W1 finish date is before W0 finish date, it means that the delays are from client, so we go to W2 finish date (to take the actual progress into consideration) and take the earliest finish date from W2, W1, W0.
I hope i did not make it complicated 🙂