You can setup the IDM Connector to apply a filter during aggregation by using the FilterTerm Rule.
Using the FilterTerm Rule should return a list of SPML's FilterTerm objects. Here is an example of applying this rule:
<Source>
<![CDATA[
import org.openspml.message.FilterTerm;
List filterTermList = new ArrayList();
// Build your term(s)
FilterTerm term = new FilterTerm(FilterTerm.OP_EQUAL);
term.setName("hasCapabilities");
term.setValue("true");
filterTermList.add(term);
return filterTermList;
]]>
</Source>