Opening RTF with index including subkeys fails

The genealogy program I use generates a family description in RTF format. It includes indexes with two levels of keys. An example of such an index entry is:

{\v {\xe {Dierkes:Maria Aleida (1852-1931)}}}

If an alphabetical index is generated, the two keys, before and after :, are merged together and shown in the index. Moreover, each entry in the index takes two lines, one containing the both keys and one containing the page numbers on which it appears. The index entry above translates to the following lines in the alphabetical index:

DierkesMaria Aleida (1852-1931).............................................
..................................................................................................1

If the same RTF file is handled by OpenOffice Writer, version 4.1.2, the alphabetical index is correct. It looks like:

Dierkes.......................................................................................
   Albertus (1922-2000)....................................................3, 5
   Maria Aleida (1852-1931).................................................1

Is there a way to get the alphabetical index xorrect in LibreOffice, in other words, does LibreOffice needs some non-default parameter settings to generate the index correctly, or does LibreOffice handle a multi-level index entry from an RTF file incorrectly?

Did you ever solve this problem?
I have it with 6.4