Nested projects vs excecution error in child project : how to stay on child and not loose the process flow

[shepardx]

Hello,
I've build a project using the nested projects way (ProjectInProject)
My concern : each time, an error occurs into a child project, the path is lost, i've to manually run the successive broken actions, and help project make to go back to the source project that launches the current one
- run to finish the fixed project,
- than manually launch the project project from the point it waited inputs from the fixed project.

Example :
- P1 / Main project (launcher) , launches P2
- P2 / some actions, and launches P3 for some tasks
- P3 / custom task, need to be back to P2, launches P4 in some cases
- P4 / custom task, need to go back to P3

If P3 has an issue, we are automaticaly back to P2 (the project that launches it).
If we fix P3 and run it again from the aborted task, we loose the return path to P2

Example of abord causes :
- Network Bandwith down, that stops some actions (Pause action cannot rely on networks/speed conditions)
- Special case detected in case of large data gathering
- etc.

>> I want P3 to halt in case of failure, so i can investigate and fix, and more important, not loose the return to P2
Or maybe i make a wrong usage of nested projects ?

thanks in advance for your advices !