Adding a file share service to Thunderbird

[JD]

Often I want to attach a file that is larger than what google will allow,
a limit I configured in TB. And TB will prompt me to use a file share 
service.

The problem is I do not want to use the 2 file share services that TB is 
showing,
and none of the add-on have my preferred file share server.

Has anyone somehow overcome this "apparent" limitation of TB, and configured
TB to use a file share service other than what TB and the plugins (add-ons)
provide?