For the unknowing;
Fusing fiber splices is somewhat an art and can be complicated. It really depends on who does it. It’s certainly not like coper.
Fusion for a splice is the process of permanently welding two optical fibers together end-to-end using a localized heat source, typically an electric arc. It minimizes light loss and reflection, resulting in a joint as strong as the original fiber.
A coupling works as a work around, but you really want a solid line.
In live sound productions, everything is portable, we have the convenience of running a backup line. In fact the mixing consoles are constructed with inputs fir Primary and Secondary lines. Cat5 or fiber.
Not sure the option is available in ISP installs. Even dbl strand, If ya cut one you’ll probably cut both anyway. I’m about to get fiber, I’ll find out lol
The stuff is expensive. I remember in early 2000s for a 350ft line from console to amps we paid $5k. When you have that investment you want it done right.
Probably smart getting an outside contractor with experience.