for mounting a macFUSE has the option allow_recursion
By default, macFUSE does not allow you to mount a macFUSE volume on a directory that itself resides on a macFUSE volume. Such recursion can create interesting unmount-time issues in some cases. Unlike most other macFUSE restrictions, this is a "soft" check that's done only by the mount program. allow_recursion disables this restriction.
if the restriction exists on linux there is probably a libfuse equivalent flag
however I recommend seeing if rclone combine can achieve the desired structure