I doubt that Bomber Command Losses can add much to the already extensive information that you have gathered regarding the loss of your grandfathers Halifax. However, I'll type the entry below just in case:
Halifax III NA237 ZA-C took off Melbourne 1831 on op to Magdeburg. Shot down by nightfighter and crashed 2230 at Hörsum, 20 km SSW from the centre of Hildesheim. Those who died rest in Hannover War Cemetery.
F/O A J Marshall + Sgt A H Griffiths + Sgt W F Paxton POW F/Sgt K D Lawrence POW F/Sgt D H Elsome POW Sgt J Thornley + Sgt R C Tuck POW
Presumably you have been in contact with 10 Sqdn Association and the Ex POW Association for further details about the POW's who survived?