Perhaps you should try some spelling variations:
"heir apparent" » "huir apparent", "her apparent", "hair apparent", "heir apparently", "heir aparente"
"heir parent" » "huir parent", "her parent", "hair parent"
"heir parental" » "huir parental", "her parental", "hair parental"
"weir apparent" » "weir apparently", "weir aparente", "weis apparent", "wei apparent", "weil apparent"

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 ("weir apparent"))) OR ((("heir parent") OR ("heir parental"))))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"heir apparent\") OR (\"weir apparent\"))) OR (((\"heir parent\") OR (\"heir parental\"))))".
• Removing quotes may allow a broader search: (((( heir apparent ) OR ( weir apparent ))) OR ((( heir parent ) OR ( heir parental )))).
• Adding a wildcard symbol may retrieve word variants: (((("heir apparent") OR ("weir apparent"))) OR ((("heir parent") OR ("heir parental"))))*.