It is not unusual for an elderly client (person setting or amending a will or trust) to bring his or her son or daughter to their estate planning appointment. The client wants the support of the family member. Unfortunately this strategy can go wrong for the favored beneficiary.
The attorney's role is to implement his or her client's wishes. Since the client is the one having his or her estate plan prepared, the attorney must follow the wishes of the client and not the wishes of the child. Most of the time this is not a problem because the child is understands and does try to coach his parent. Occasionally some children believe that their parent needs their help in order to properly express the client's wishes--ironically, it is often when the child that is present is clarifying that the client wants to exclude one or more of the client's children that are not present.
Over the last 30 years we have meant with many clients who have clearly expressed their desire to exclude one or more of their children in their estate plan. And we accomplished this for them with language that demonstrates that the child was not forgotten by the client and thus under the law be deemed to be an omitted heir. However, the expression of intention MUST come from the client and not anyone else.
It is our recommendation that if you plan to favor one child more than the other children, you don't have the favored child bring you to the appointment. The risk is that a disinherited child can argue undue influence and this is a grounds for contesting a trust or a will. If it is absolutely necessary to have the favored child bring you to your appointment, then the child should stay in the car if possible or at a minimum wait in the lobby. This actually protects the favored child because it reduces the argument for undue influence.