Why? ACLs permissions are fragile in my hands and this works a lot better, IMO. Despite caveats.
Install resilio sync and run it as its own user
sudo apt install bindfs
sudo mkdir /home/rslsync/tamas-sync
sudo chown rslsync:rslsync /home/rslsync/tamas-sync
add the following line to /etc/fstab:
bindfs#/home/rslsync/tamas-sync /home/tamas/sync fuse force-user=tamas,force-group=tamas,create-for-user=rslsync,create-for-group=rslsync,perms=u+rD:go=
Here we take the tamas-sync folder in the rslsync user's home directory and mount it in my home directory as sync.
We also force all files to behave like they're in my user and group. Conversely any files I add will also be created
for the rslsync user and group (the create-for options).
!!! note One annoying thing is that the Dolphin file browser doesn't seem to know that the changes have happened so you need to hit F5 to refresh. This is due to a limitation of FUSE.