Housing costs paid under PC when shared liability

Can anyone clarify a point that arose in discussions yesterday with a client?  We established that she is entitled to a small amount of guarantee PC and her mortgage is currently in her name only.  She lives with her two adult sons who are both working and they have all decided to change the mortgage into their 3 names, to give equal shared liability.  This process is already in place and client is happy about it - however, will she be entitled to her share of mortgage interest being paid under her PC claim?  The information provided in CPAG is confusing on this issue.

The other point is that for CTB, her sons will not be classed as non-dependants once they are co-owners of the property (CPAG pg 870) - how will this impact on her CTB entitlement?  Many thanks.

CPAG pg 848 - the issue appears to be around ‘close relatives’ but directly above that line, client meets the criteria for ‘treated as liable’

Thanks Tony.  I think we have effectively interpreted it in the same way and I appreciate your response.  We will proceed with her application for PC and her share of the mortgage interest.  I will post any relevant points or developments!