I have read most of the posts here involving this problem of synchronizing. I have tried many things to get one of my largest trees to synchronize and nothing has straightened it out. It keeps telling me to create another tree to link. What happens to all the others that I have. It is frustrating to have to keep redoing. It copies sources 3 and 4 times and I waste my time correcting these. On the last tree I did, I refused to invite anyone because I don't want others to have problems also. I wish they could provide some way to indicate what the problem is. If it is truly theirs, then fix it so a person doesn't feel like one has spent so much money and then has to lose data and has to start over. If I have actually made an error, I would like to know what it is so that I can correct it.