Hello!
The medical report of other family members if found unremarkable by the clinic will be sent to the VO and processed accordingly. You need not worry about your son's part of the application.
For your part, you need to send whatever docs they ask for even with the delay in the med clearance part because processing of applications does not follow a set process. From what I've experienced, once the VO knew about the delay in my daughter's med part, they proceeded to process other parts of our application such as criminality and security checks, etc. Our VO, which was CEM, had to call me at the tail end of my baby's treatment because they had probably done all other parts of the processing and was just waiting on her med report.
As long as you inform the VO of what's going on with you, and surely the clinic does provide partial reports of ongoing medical clearance processing, just let this take its course. And pray...
I hope this helps. Take care and good luck.