Stopping of AA and effect on non-dependent deductions

I recently took over a case where a couple, both over 65 and one of whom had been awarded AA in June 2010, were getting GC and therefore full CTB. They have an adult son living with them (not sure if he was there before the AA was awarded) who earns over £500 pw gross.  No non-dep deds due to the AA.  The cl getting AA died in March 11.  The Council know about that and the subsequent change of income for the partner, meaning she just gets SC now and has to pay some CT, but I spotted that the Council haven’t levied any non-dep deductions as a result of the AA ceasing.  Is the son perhaps ignored for 26 weeks in those circs?  I am assuming the Council know about the son.

Is the son a co-owner by any chance?

The cl owns the property but the son pays the mortgage.

I was trawling through the internet and came across a DWP document A5 - Calculating Benefits - that answers my question.  See below.

Changes related to the claimant
P5.683 The 26 week deferral provisions do not apply if the claimant has a change of circumstances
that would mean a higher non-dependant deduction.
Example
A non-dependant lives with elderly parents, one of whom was entitled to AA.
AA entitlement has now ended. Make a non-dependant deduction immediately –
this is because the change of circumstances is related to the claimant, not the nondependant.