Heirs entitled to a mandatory part can renounce the entitlement.
German inheritance law is complicated. The legal succession provides basically a large group entitled to a mandatory part.

Notarized, however, the heir can renounce his mandatory part.Bremen. Anyone who is excluded from the legal succession by a will or a contract of inheritance, as a direct member, continues to be entitled to the compulsory portion, the Bremen Chamber of Notaries says. This corresponds to half the value of the statutory inheritance.
If a beneficiary wishes to renounce his compulsory portion, this must be agreed in a notarized contract by both the testator and the heir. Important to note: The testator must be present at the certification. The heir to the inheritance, on the other hand, can be represented.
A waiver of the ordinary part of the obligation additionally affects all other claims based on the compulsory portion law. This includes compensatory and additional compulsory parts as well as additional claims. Possible heirs of the heir to the inheritance are excluded from the compulsory portion as well.
Josef Langenburg LL.B.
German genealogists & international probate researchers