I’m not sure if a single Speckle stream can be received and sent at the same time (I don’t know as much about speckle as I should, I just help develop the Unity plugin) but here’s what I do know:
There was a sending API written by the original author @cwm but it didn’t perform well at larger scales and was disabled until a more scalable solution could be found. You can downgrade SpeckleUnity to version 0.2.1 in the package manager or clone this version of the source code: https://github.com/speckleworks/SpeckleUnity/tree/c86f55d8701facc0014a5fdbf61d94029bedf4f8
This version contains an older workflow where there were prefabs set up for managing, sending and receiving separately as opposed to the new workflow featured in the documentation. There’s even example scenes for sending speckle streams.
The big BUT in all of this is that Chris only got sending to work for points (positions) and single number values. Not whole meshes. Also, since sending and receiving were coded to work separately, you’ll need to handle copying the received objects over to the sender to then be manipulated and then sent back up. So you’ll need to do a fair bit of leg work anyway.
I’m developing the unity package to be aiming for feature parity with the web viewer (readonly) first since it’s much more straight forward, gets the most features into the package and can be considered production ready much sooner as well (the package is still very much in preview).
In the off chance you do develop you’re own solution please make a fork of the repo and share it with us!