Why can't I merge duplicates on FamilySearch Family Tree?

The title to this post is one of the questions asked most frequently about the challenges of working with the FamilySearch.org Family Tree. Unfortunately, the answer to the question is complex. There are presently six basic reasons for the inability of the program either to merge obvious duplicates or to fail to find duplicates at all. During the past year, FamilySearch has implemented numerous safeguards in an attempt to cut down on the number of duplicate ordinances and it would seem that one way to achieve this goal would be to implement an effective way to eliminate duplicate entries in the Family Tree. Despite this avowed goal, it seems that months and now years pass with little or no progress in this regard. 

There are some serious issues that must be resolved before the merge function of the Family Tree program will work properly. It is now almost a year since any update to "Using the FamilySearch Family Tree: A Reference Guide (18 October 2013)" was made. Despite that lapse of time, the explanation for the inability to merge duplicates still applies. Quoting from page 146 of the Guide:

Records That Cannot Be Merged 

Some records in Family Tree cannot be merged. You cannot merge records in the following situations:

• The gender on one record is male, and the other is female.
• One record indicates the person is alive; the other is deceased.
• Both records come from the membership records of The Church of Jesus Christ of Latter-day Saints.
• One of the records came from new.familysearch.org, where it has been combined with too many other records.
• The duplicate record has already been deleted due to another merge.
• One of the records has restrictions that would prevent it from being changed. 

If Family Tree has already identified possible duplicates that cannot be merged, they appear beneath the list of possible duplicates.

All of these six reasons still exist, even after a year since they were last updated. There are some few changes however that effect the seriousness of the items on the list. However, this issue is addressed in the Help Center, available from the "Get Help" link on every page of the Family Tree. The entry in the Help Center is entitled "Cannot merge duplicate records in Family Tree." 

The first of the issues above concerning conflicting gender information has the longest and most involved explanation. You can see the answer in the Family Tree Product support article entitled "Correcting gender information in Family Tree." 

The next issue combining a living with a deceased individual has the following explanation:

One record is a living individual (records of individuals born within the last 110 years that do not have death information). If you were allowed to merge these records, then the individual's record would be treated as if he or she were living. Only users who are directly related to the individual would then be able to see the record. This might prevent you or the original contributor from seeing it. 

If the individual is deceased, update the living record so it shows as deceased. Then you should be able to merge the two deceased records.

The issue of the membership records is addressed separately by the Help Center explanation reference above and requires contact through the Feedback link on the bottom of the page. You will need to be signed in with an LDS Account to see these member oriented explanations.

The issue of the origin of the records from new.familysearch.org is ongoing. The present explanation is as follows:

One of the records for the individual is too large

• These records are often referred to as IOUS, meaning "Information of Unusual Size."
• Presently, other records cannot be merged with an IOUS record nor can IOUS records be unmerged.
• This is a known issue, and there is no estimated time for a fix.

 Note, this is a change from the original definition of an IOUS which always has been "an individual of unusual size."

The remaining two issues are also still a problem and there are links to the more complete explanations. Again, you may need to be logged in with an LDS Account to see some of these additional explanations.

There is also a note as follows:

NOTE: When merging by ID, the ID numbers MUST use capital letters and include the dash between the numbers. For this process, see point 4 in Merging Duplicate Records in Family Tree (53952).

More on this issue in another post.