Create Task depending on another task status created by flow

Hello,

this is my requirement:

-After creating a new Project, Task#1 is automatically created.   -After that Task#1 is closed, create automatically 2 more tasks (Task#2 and Task#3).  -When Task#2 and Task#3 get updated(Closed), another Task#4 should be created.       For now, I have created 2 flows, and I starting to create a new one for Task#4. Do you have any suggestions on best practices and how can I solve the last point(create Task#4 when Task#2 and Task#3 are closed)?   

 Thanks