The "Dictionaries" sub-node of "ServiceManager" can have multiple entries.
If you already have one "HunSpellDic_mr_IN" then you can create one more "HunSpellDic_mr_IN_private" like this...
<?xml version="1.0" encoding="UTF-8"?>
<oor:component-data xmlns:oor="http://openoffice.org/2001/registry" xmlns:xs="http://www.w3.org/2001/XMLSchema" oor:name="Linguistic" oor:package="org.openoffice.Office">
<node oor:name="ServiceManager">
<node oor:name="Dictionaries">
<node oor:name="HunSpellDic_mr_IN" oor:op="fuse">
<prop oor:name="Locations" oor:type="oor:string-list">
<value>%origin%/dicts/mr_IN.aff %origin%/dicts/mr_IN.dic</value>
</prop>
<prop oor:name="Format" oor:type="xs:string">
<value>DICT_SPELL</value>
</prop>
<prop oor:name="Locales" oor:type="oor:string-list">
<value>mr-IN</value>
</prop>
</node>
<node oor:name="HunSpellDic_mr_IN_private" oor:op="fuse">
<prop oor:name="Locations" oor:type="oor:string-list">
<value>%origin%/dicts/mr_IN_private.aff %origin%/dicts/mr_IN_private.dic</value>
</prop>
<prop oor:name="Format" oor:type="xs:string">
<value>DICT_SPELL</value>
</prop>
<prop oor:name="Locales" oor:type="oor:string-list">
<value>mr-IN</value>
</prop>
</node>
The actual location where the files like "*_private.dic" are stored is not known. The words from private files are still considered correct and hence the location does not matter. This will help you to group words into different categories.