Hugh's step-father's will says:
SUBJECT as above (Executors to hold his Estate upon trust) my Executors shall hold my Estate
1. for my said wife Elizaeth Murray absolutely if she shall survive me by 28 days and PROVIDED that the gift shall not otherwise lapse
2. Subject as above for such of my children TGM ..., JDS ... and CJM ...and my Step-son Hugh La Trobe ... as shall survive me and if more than one in equal shares absolutely.
My Executors shall in addition to an without prejudice to all statutory powers have the powers and immunities set out in the Schedule provided that they shall not exercise any of their powers so as to conflict with the beneficial provisions of my Will.
The step-father then did a codicil giving £5k to each of Hugh's 3 children and saying
2. I HEREBY REVOKE Clause 5.2 of my Will and substitute therefor:
SUBJECT as above my Executors shall hold my Estate for such of my children TGM ..., JDS ... and CJM ... and my step-son Hugh La Trobe ... and my Granddaughters KM and AM as shall survive me and if more than one in equal shares absolutely.
Hugh's mother was the executor of her husband's will. It doesn't seem to say anything about if she died before him.
Does this help at all?