Automatically store based on file size - linux - bcache?

Hoping to get answers to this on **Debian** based distros: When saving a file, from **any** program, I'd wish to know if it is possible for the OS to automatically save based on file size. For example, imagine a system with a "big" HDD and a "small" SSD (the OS being installed on another SSD) so, If a create, copy or move command is issued on a file larger than say, 100 MB, save that file to the HDD, otherwise to the SSD. I know there are caching solutions that place frequently used files to the cache storage, but that's not what I want. I want all files smaller than some amount to be stored in the "small" SSD **without user intervention**, no matter from what program the file is created, as long as that file is created by the user. **Can this be done in Bcache** (or any other solution)? P.S. This requirement is only for **user data** files (documents, photos, movies, downloaded files). I'm not interested in OS, program or system generated files... let those decide their own location in the system mount drive. Also, I would like the solution **not** to "make a copy" on the cache, I do not want to have duplicates. A separate backing solution would do this.