Merging Cells in Markdown Tables

I am trying to make some fancyish tables in a Discourse post and cant seem to get it to work. In a nut shell I want to merge some cells to place multiple cells underneath or similar. Is this possible?

This is my syntax

| | Grouping ||
First Header | Second Header | Third Header |
------------ | :-----------: | -----------: |
Content | Long Cell ||
Content | Cell | Cell |

This is what I get

| | Grouping ||

First Header Second Header Third Header
Content Long Cell
Content Cell Cell

This is what I am trying to do

image

Any advice is appreciated!

That seems like a copy paste of multimarkdown example.

And I think Discourse is using markdown.it. Therefore not possible to do in Discourse.