I have added a tab to a channel (using the website option) showing the folder within our business level sharepoint document library, but there is no way to attach a file from this subfolder to a conversation, the only options are upload from my computer, my own Onedrive folder or Browse Teams or channels.
It seems ridiculous that there are such limited options.
If you need to use the browse files option instead of using Sharing links or what not, you can go to your Files tab of your Team, click on "Add cloud storage" and pick SharePoint out of that. Then go link your Company document library to your Files tab, and then you'll be able to link files out of your Teams library.
Thanks Chris, that seems to work, however, it seems you can only select a folder from the top parent level and not anything further down the hierarchy. We have nearly a TB of images in a folder within the documents folder so at 2 levels down, but can only add the highest folder i.e Documents not documents/pictures.
Might have to wait till the SharePoint files tab integration comes out to see if we get something for this. Until then your only option might be just using the copy link option on the files and pasting them into conversations until we can hopefully get some better file linking functionality.