Is it permissible for a man to bequeath to his deceased son's daughters that they "take their father's place in everything," and that their share of the inheritance be the same as their father's would have been had he been alive?

It is permissible for the grandfather to make a bequest to his deceased son's daughters if they are not heirs (i.e., disinherited) provided that it does not exceed one-third of the inheritance. This is also commendable for him to do. However, their share must not exceed one-third unless the heirs agree. If they are heirs, then a bequest to them is not valid, based on the hadith: "There is no bequest for an heir." The validity and enforceability of the bequest depend on the status of the son's daughters at the time of their grandfather's death.