It is not unusual that one child is closer to a parent or parents. It would not be unusual when the parent decides that it is time to prepare a will or other estate planning documents that the parent would call on that child to assist. The parent may ask that child to provide the name of a trusted attorney or other assistance in the planning and preparation of these documents.
The risk is that when the parent passes, the other child(ren) may create family disharmony that will never subside. The problem may come from a sibling or an in-law. There is one thing that can be done to possibly avoid this situation.
That one thing is communication. Communicate with each child during the estate planning process. Encourage each sibling to discuss this matter with their spouse or partner. Ask each sibling to communicate to all other siblings their concerns, especially if a sibling feels that the parents have made a promise to that sibling which may be compromised by the intended estate plan. If a sibling raises concerns, ask that sibling to have the documents reviewed by the sibling’s attorney and do keep each email that you send or receive on this topic. Forever.
The time and cost that you spend now is small compared to the time and cost of probate litigation and if nothing else, you will have the peace of mind that you tried to avoid family conflict.