No will for an heir

Yes, that is permissible. Shaykh al-Islam [Ibn Taymiyah] (may
Allaah have mercy on him) said: “It is not permissible to make a will
leaving something to an heir without the consent of the other heirs. Heirs
may be included in the will in general terms without mentioning them by
name.” (al-Ikhtiyaaraat, p. 190). 

What this means is that if a will is in general terms, i.e.,
it does not mention people by name, such as one that mentions categories,
such as the poor, or students, or mujaahideen, etc., it is permissible for
those who fall into those categories to take something from this bequest
even if they are also heirs. But if the will mentions people by name, such
as bequeathing wealth to relatives, the heirs cannot be included in this
bequest. 

And Allaah knows best.