[Koha] CDS/ISIS to MARC21 (Koha) issue

Dear colleagues, I'm trying to convert (using MARCEdit) my approx. 10 000 entry ISIS database to MARC21 for import in Koha. I'm encountering the following problem: Some of the tags for each book are duplicate; for example, for multiple authors, the record will look smth like this: ... =702 John =702 Mary =702 Ann ... I would like to merge this fields into the MARC21 100 field like this: ... =100 \\$a John, Mary, Ann ... Unique fields haven't posed problems, but those duplicates do. I would really appreciate some help. Best regards ^_^, -- Alexandru Constantin Student Computer Science @ University Politehnica of Bucharest http://crasheralex.me