I understand it could be complex to implement, but it's a much needed feature!

On our project we need the same thing and it's quite complex to achieve.

I don't know if it can be helpful somehow, but at this time we are trying to do this via a Grid by hardcoding the headers in the xaml.
We will have to reimplement some of the DataGrid mechanisms to populate the data, and I am afraid it will require a lot of work.

Hi @otrebla-snake-ita - as mentioned in the pinned issue - we only have the resources to work on TreeDataGrid for paid customers. However I can see that grouped column headers is a useful feature. Please let us know here if you would like to help fund its implementation.

I started working on this feature a time ago, but it's still in its early stages. If you want to continue it, I share the branch.

@workgroupengineering it would be really appreciated!

@grokys thanks for the info, will see if we can help somehow in the future! :)

@otrebla-snake-ita see PR #240