It should be noted that you cannot "unmerge" (split) combined records
in newFamilySearch. This is also not functional in Family Tree.
If you have a record that needs to be split, the only way it can be
done currently is to open a case with FamilySearch.org and indicate
the persons (including their PIDs) involved.
You should not attempt this, except in the case where two separate
people were combined into the same record and each likely has
ordinance work that has been done. I have one such case open right now
to take care of this problem: There are only two people, one with
three records and other with six, that need to be split. They were
sisters married to the same husband, and have similar given names.
Because the combined records were created in newFamilySearch, the
Family Tree instructions for splitting records do not apply.
If you have an ancestor with many, many combined records, then use
Family Tree to indicate which data is valid and why. You can delete
duplicate data as well, thus cleaning up the record in Family Tree.
Actions of this nature are not reflected back through to
newFamilySearch. You can also select which vital information (name,
dates of birth and death, and where buried) is correct through
Because Family Tree is still in the process of development, you can
expect the situation to change from time to time, but I thought I
would pass on what I've discovered as of this date.