Perhaps you should try some spelling variations:
"heir apparent" » "huir apparent", "weir apparent", "hair apparent", "heir apparently", "heir aparente", "heir apaparente", "heir apparental"
"heir apparental" » "huir apparental", "weir apparental", "hair apparental", "heir apparentlyal", "heir aparenteal", "heir parental", "heir apparently", "heir aparentan", "heir apaparenteal", "heir apparentalal"
"heir parent" » "huir parent", "weir parent", "hair parent", "heir aparente", "heir parental"
"her apparent" » "her apparently", "her aparente", "her apaparente", "her apparental"

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (((((("heir apparent") OR ("heir apparental"))) OR ("her apparent"))) OR ("heir parent"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((((\"heir apparent\") OR (\"heir apparental\"))) OR (\"her apparent\"))) OR (\"heir parent\"))".
• Removing quotes may allow a broader search: (((((( heir apparent ) OR ( heir apparental ))) OR ( her apparent ))) OR ( heir parent )).
• Adding a wildcard symbol may retrieve word variants: (((((("heir apparent") OR ("heir apparental"))) OR ("her apparent"))) OR ("heir parent"))*.