How to get PlcSoftware from context menu (AddIn) (TIA Openness)?

Hello, 

I am working on an Add-In for TIA portal V16 in Visual Studio. I have essentially combined two of demo projects up to this point to get a very light baseline that can be compiled and tested in V16. The project I am basically working off of is the template for V17 from this webpage https://support.industry.siemens.com/cs/ww/en/view/109817270. 

So, I have the context menu working and I am trying to export a block. Page 486 of this document (https://support.industry.siemens.com/cs/ww/en/view/109477163) shows how to export a block, but it requires a reference to PlcSoftware plcSoftware. This seems like it should be simple to get a reference to parent objects from the context of where the add-in selected, but I haven't found a way to do so, so far. Any help would be greatly appreciated!