Inherit default color in highlighter

Is there any way to extend existing highlighting colors? I developed plugin for custom language which has 2 kinds of variables I want to distinguish:
- block variables
- global variables

 

I would like to color them with the same color as DefaultLanguageHighlighterColors.INSTANCE_FIELD has, but make global variables bold. I created MyLangHighlighterColors object:

object MyLangHighlighterColors {
    val BLOCK_VARIABLE = TextAttributesKey.createTextAttributesKey("BLOCK_VARIABLE", DefaultLanguageHighlighterColors.INSTANCE_FIELD)
    val GLOBAL_VARIABLE = TextAttributesKey.createTextAttributesKey("GLOBAL_VARIABLE", DefaultLanguageHighlighterColors.INSTANCE_FIELD)
}

 

and colorSchemes/MyLangDefault.xml:

<?xml version='1.0'?>
<list>
  <option name="GLOBAL_VARIABLE">
    <value>
      <option name="FONT_TYPE" value="1"/>
    </value>
  </option>
</list>

 

I registered it in plugin.xml:

<additionalTextAttributes scheme="Default" file="colorSchemes/MyLangDefault.xml"/>

 

Unfortunately global variables doesn't have INSTANCE_FIELD's color. Is there any way to inherit color from INSTANCE_FIELD and overwrite only font type (or other) option?