Living children include all biological and adopted children of a Testator, who is alive on the date of making this Will.
A trustee of a will is the person legally appointed by the deceased (testator) in their will to manage and distribute their estate.
This involves carrying out the instructions in the will, paying debts and taxes, and distributing the remaining assets to the beneficiaries.
All the residue can be put back in the trust, distributed between your family members or friends, given to the charity etc.