Thanks Beximco.
I got opposite views from other members. Not sure which one is correct.. please have a look... let me know if there is any link for 1 year validity requirement.
From Palakpatel911
1. not now, wait till you get stamps on his as well.
2. Nope
3. with main applicant only if the requirement is fulfilled, then i guess not required even later also at NDVO. (for your spouse ielts)
From mabmabs
No need to do any action now, depends on your case. If you receive MR in few months time, it should be ok, otherwise, you can renew your son passport by next year in July/August (if you didnt hear from visa office for MR request), Please update visa office if you renew your son passport.