FamilySearch is one, big "shared family tree." You do not have a private family tree like you do on Ancestry. People change information all the time, especially LDS Church "volunteers." If they want something to be a certain way, they will keep changing it and changing it, and in addition they may send you threatening messages telling you that you cannot place any information on that part of the "shared tree"--it is only "shared" for them, not you. They have even done this to my grandmother, with whom I lived. Overnight all your cousins from a certain part of your family may disappear because someone has combined your grandfather and great grandfather into one person because they both had first names starting with the letter T (for example), never mind that their birth dates were 40 years apart. I could literally give you 1,0000 personal examples...

My understanding from the course from my church I attended by a counselor is that your family tree is only seen by you. Those who've died are public information. If you see something not correct, you can ask FamilySearch to investigate and then remove the info., an example is when a family member was erroneously listed as having died when they are actually living.

I am not sure WHO has done it but it happens to me all the time.