DLA - change of circumstances, supersession and effective date?

Client already in receipt of DLA LRM/MRC (mental health problems) at the point that he falls and breaks vertebrae in lower back - mid-October 2012. Some delay in obtaining treatment/diagnosis and eventually enters hospital 31/10/2012. Discovered that has two serious (and extremely rare) infections in area either side of fracture. Between 1/11/2012 and 18/1/2013 has a series of operations to wash out and drain infection as it returns and spreads. Both the break itself and the operations result in nerve damage. Complicated by a DVT and septic shock whilst in hospital. Now has Cauda Equina Syndrome meaning very little sensation from waist down - any walking with a frame and needs to use both hands for this at all times. Any distance beyond 20 metres needs wheelchair.

Existing payment of DLA suspended/moved to underlying entitlement while in hospital.

Will undoubtedly now meet conditions for HRM/HRC but…....

He requested supersession form in anticipation of discharge, leaving me insufficient time to complete within a month.

What prospects for an argument that actual change of circs did not happen until discharge? i.e. not until he returned home and was trying to cope on his own did the full extent of his changed care needs become apparent? This would allow me to get application in within the month….