Realtime/RunTime Spline Generation

I’m trying to make a proof of concept, where the user selects an origin (the red cube) a destination (the blue sphere) via the drop down. Once selecting the origin and destination, it’ll generate a spline and move a green cone along it. I’m trying to create a Real-time Spline Generation system. Each drop down should reference it’s respective mesh so it can give the location to the spline manager. This is how far I’ve gotten with the help of several chat-bots, and tutorials but I’ve ran into a few errors and I’m not even sure if I’m heading in the right direction.