"For the purpose of ascertaining entitlement under this Will any beneficiary who does not survive me by thirty days shall be treated as having died before me.  "
The above is a clause one usually puts in one's Will to mean in layman terms:
If any of my beneficiaries DIE AFTER I DIE WITHIN 30 DAYS TIME is to be out of my Will (coz i treat them as DEAD BEFORE I DIED)

This is usually done to ensure that only my INTENDED beneficiaries OR their alternatives which i've stated in the Will, get what i want to give them, NOT THEIR beneficiaries.
eg.
I put my daughter and sister as beneficiaries 50% / 50%
+ that 30days survival clause
+ alternative to my sister is my mother (ie if my sister not around, 50% goes to mum)
Scenario 1: I die, everything goes smoothly to my daughter & sister
Scenario 2: I die AND my sister dies within 30 days of my death, my daughter & mum gets 50% 50%, NOT my sister's husband, kids, etc which is in her own Will.
Without that survival clause in my Will, 50% of my net worth will go to my sister then she kaputs and then her Will kicks in, moving her net worth (which is now +50% of my net worth) to her beneficiaries - chain of death/Wills thinggy

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As for the fraud thing - there's something weird with the data U provided.
U stated (i may have misunderstood yar, please correct me):
a. A & B = joint-executors
b. A & B also beneficiaries to get 50% 50% of deceased net worth
c. B sapu-ed 100%
er.. if the Will states item (a.) and (b.) above, A can go after B's butt leh.
Whether B committed fraud or not needs to be proved in the courts - mana tu Will? A tak de copy ke?

Blasto-san, IMHO, if the sum that A is to get is like >$200K, better look around for litigation lawyers well versed in estate law & investigations.

If A already has proof (last copy of Will, data on shares, deposit boxes, debts (remember minus debts ar), etc.) that B "swallowed" more than fair share, it should be a winnable case - just that if B is going to fight all out, it may go all the way up to the court of appeals, thus the "results" better be worth more than $100K+ (expected cost).

Er.. the sum of $100K+ is based on my own digging if i were to fight and destroy my ex for my daughter's custody in court, all the way up to the court of appeals. Sigh.. one sure as heck learns a lot during turbulent times
Thus, A's cost may vary a bit. If cost is an issue, perhaps nego with lawyer as a % of the estate lar - if the estate is huge.

As for the "joint executor must have joint account", i'm unsure - i've not died yet nor been an executor yet (appointed but appointor havent kaput yet) so far heheh

Side note:
If the deceased is a Muslim, all the above may be moot as the Faraid and stuff will overide whatever Wasiat placed. If i'm not mistaken, for a Muslim, a Wasiat is just one's wishes and CAN BE OVERRIDDEN by Faraid and other Muslim estate laws.

Hey Blasto. Er.. heheh U "see me too high" leh - i'm no lawyer, just a bit read & experienced with Wills and Wasiats. Thus, i'm unsure how cheating of a Will is categorized but i'm dead sure it's at least similar to a breach of contract OR at worst a CBT.

Best to get a legal view on this - somewhere in LYN i think is a Legal topic OR there's a forum for legal Qs somewhere (M'sian legal) i've bumped into before. My bad - getting old, memory's not what it used to be

A win & B no $ to pay? Assets ada? Can garnish? If not, then A would do it out of pure justice only lor - thus, like i mentioned, negotiate / get a legal eagle to work for a % of $/assets that is recovered. Trust me - it aint a comfortable life with a legal eagle hounding one (if B claims no $ to pay). The only Q would be whether A can tahan all that "wasted time, effort and resources" to go after B's butt. There are other ways to make B's life hell... which cant see the light of day in a forum