With version 2.7.3 it is now possible to do this by following this simple process:

1) open the document where you want to past markdown content

2) place the caret to the position where you want to insert it.

3) click on "insert" or press cmd+i

4) choose markdown section type

5) paste your markdown into the markdown section

6) click the merge button on the right side next to the markdown section.