Your estate planning attorney can only help you to the extent that you help your attorney understand your situation. If you are not forthcoming about every relevant detail you could ultimately wind up with an estate plan that is not optimally prepared.
For example, last year the actor Sherman Hemsley, who is best remembered for his role as George Jefferson, passed away after battling cancer. A man name Richard Thornton suddenly appeared out of nowhere to challenge the will. After DNA testing was ordered by a probate court judge in El Paso, Texas it was determined that Thornton was in fact the actor’s half-brother.
In the end the validity of a will that left everything to a close friend of Hemsley was upheld. However, the matter was hung up in limbo for a good bit of time, and Hemsley was not laid to rest until months after his passing.
If you have any long-lost relatives out there you should certainly let your attorney know about them. This is also true of former spouses, or children that you may have that your family members may not know about.
The existence of any premarital or post-marital agreements will also be relevant when you are planning your estate.
There is an attorney-client privilege, so anything that you say is going to be kept in the strictest of confidence.
If you are upfront with your attorney as you explain everything in detail you can go forward with total peace of mind knowing that there will be no unpleasant surprises presenting themselves after you pass away.