RetainConnection will not help you. Each child package has it's own connection manager. The fact that they have the same name does not mean anything.

So, you need to use the package transactions. These do use MSDTC. So, you need to ensure DTC is configured correctly on the server running the SSIS packages and the database servers they are connecting to.

Since your package is actually running (and hanging), it is probably configured ok.

Make sure the packages do not conflict with each other. Since everything is hanging, I would suspect a DTC deadlock. Make sure you are not reading data that is being written to - keep lock escalation in mind.