This is a canned answer, it may not be exactly the answer to your question.
Merging....go to the parent's profile, click on the yellow/orange Edit tab.
On the right you will see a column of names under Chldren.
Somewehere below this you will find a green [show merge options] click on this and note that each name has a box in front of it. Click on two boxes of children with the same name and then at the bottom, click on "compare". This will take you to the compare file with both of them side by side. Confirm that they are truly duplicates, then at the top. click on Merge. This will take you to the merge page where you again have the option of comparing data. If all is correct, go to the bottom and click on Merge.
You will have to do this for each pair of names.
Yeah, it's a bear.