That alone is not going to be evidence, if only for the good reasons given by Ethel.It is extraordinarily difficult to successfully challenge a will on the grounds that the testator lacked testamentary capacity (e.g.was of unsound mind) and : did not know or understand what it was that they were executing.The courts will do their best to preserve the will because they accept that old people, in particular,may be quite perverse in their dispositions in any case yet understand what they are doing.It is obvious that the testator may forget or not know that given individuals have died but still be fully capable of understanding what they are doing in making a will. The deceased beneficiary's share will fall into the residue and be distributed accordingly , unless the testator has given specific instructions to give it to some other named individual in the event of the original named beneficiary being unable or unwilling to accept it.