Hi Ken:
These are great ideas. I'm not sure where I'd search for a South African will.
I did visit the South African archive site here:
http://www.national.archsrch.gov.za/sm300cv/smws/sm300dlAlthough there is nothing for Lonsdale Denoon Young, I did find some records establishing the appointment of Heydon Young as Postmaster of Umbilo in 1888. If Lonsdale's medal went to anyone, I expect it was to him. There is a record from MSCE (I believe this is a concerned with probate) for Heydon Charles Young, which may refer to his death. The record is dated 1912 and has S/SP Young, Isabella Mary Ann who could be his wife or daughter.
And another record for a David Heydon Denoon Young from 1913. Its source is "MHL", and I have at this point no idea what it records. But the name alone demonstrates a family connection.
Incidentally, the sister of Lonsdale Denoon and Heydon Charles Young was Euphemia Chamberlain Young who married Sir Frank Umhlali Reynolds in 1894. So, by the turn of the century three of the Young siblings had emigrated to South Africa. I'm descended from one of the two sisters who stayed behind in England - although I have emigrated to the USA.
Christ's Hospital School had no record of what had become of Lonsdale Denoon Young, and this is information that they may appreciate.
From looking for online clues to the officering of the Natal Native Contingent, I'm sure there is more in the Times of Natal during November and December 1878 as the NNC battalions were mustering. I don't have access to it. Hopefully someone on the forum will.
Alan