Don't use repeating fields for this kind of set up. Since FileMaker changed from Flat File to relational database system with the release of FileMaker 3, one should use a table of related records in place of repeating fields used in this fashion. With such a related table, your relationships and lookups become very straight forward and the reporting that you can do from such related records is much more flexible as well.
OriginalTable::__pkOriginalTableID = RelatedTable::_fkOriginalTableID
LookUpTable::__pkLookUpTableID = RelatedTable::_fkLookUpTableID
You would then replace your repeating fields wit a portal or portals to the RelatedTable.
And Import Records has an option that makes it very easy to move existing data from repeating fields in your OriginalTable into split up RelatedTable records if you have existing data you want to keep in those repeating fields.