"lost" merged tickets

I recently imported data from rt 2 to rt 3 - 3.0.7_01 and then upgraded
to rt 3.0.8. The problem I have is that some merging seems to been
undone - there about 4 tickets that were merged into 1, but that doesnt
appear anywhere. Do I have to manually merge those tickets, or can I run
the import script again and set the following to 0:


and set $import_links" to 1 in the import script.