Editing bodies that have been saved to individual part files

I have created a multi-body part file then saved the bodies as
individual parts, these individual parts are in turn inserted into
some assemblies, but after editing the multi-body part file (adding
some cuts which in turn changed the body names in the multi-body part
file) the individual part files have gotten "confused" and some are
now referencing the wrong body from the multi-body part file so that
now two of these individual part files are referencing the same body
which means that one body from the multi-body part file no longer has
an individual part file.
Does anyone know how to edit these individual part files so that I can
tell it which body I want to reference? So far I have not found a way
to do this.
Of course one way would be to delete one of the duplicate individual
part files then just re-save the missing body as an individual part
file but I am trying to avoid doing that if possible.
Thanks
Sam