How set up test code coverage with different test levels?

I'm using nyc for generating Code coverage reports. I use different levels for my tests. How I can merge reports from different levels?

There is my part of my package.json

"scripts": {
  "test": "npm run test:unit && npm run test:component",
  "test:component": "nyc mocha ./test/component",
  "test:unit": "nyc mocha ./test/unit"
},
"nyc":     {
  "extension": [
    ".ts"
  ],
  "cache": true,
  "reporter": [
    "lcov",
    "text-summary"
  ]
}