No I did not, but I have implemented a semi-satisfactory workaround. I have given the users read access and have created a different group with write access.
The problem is that, at least through the panel settings, write access allows for deletion as well. On other setups of ProFTP, I have been able to limit delete privledges as well as overwrite privledges.
I also confess I have not taken any time to explore the conf files. I was hoping someone had solved this, but it appears to not be the case.
I will post if I have any success....