Your legal estate planning tool, whether it be a Will or a Trust, allows you to identify your heirs. You can include or exclude whomever you like. There is no legal requirement that you give an inheritance to your son's family, yet no legal barrier if you elect to give them an inheritance. You must, however, clearly identify your intended heirs. The best approach is to identify your heirs by name.
Little doubt remains about who they are or what they get.
In that case, identifying who belongs to those groups is vital. A recent case in Dallas points out the potential problems. The court, upon reviewing the law, decided that Martha should inherit. According to the Texas Family Code, an adopted child is treated just like a biological child. Sarah could have avoided the problem by defining terms in her Will.