We need the ability to file share directly in chat with external users.

For context:
I have a team of contract BI developers working to build out our BI system. We often have the need to pass large files back and forth, which prohibits email use. Previously, in Skype for Business, we could drop files into the chat and pass the files directly to the person that needed it. We need this capability back - the current work-arounds for file transfer are significantly more complicated and will end up wasting a decent amount of time in the future.