Build shiny app for decision tree analysis

I am trying to build an app using shiny. My final goal is to create an interactive decision tree from three input fields (start node - end node - probability). The tree is being creating dynamically, node-by-node. Every time the user press an "Add" button a new movement is being creating in the tree. Any time the user deletes a movement (history being displaying in a data table) the tree should adapt in that action.

I have some difficulties creating a decision tree like that. Any example I found online works with a defined data frame, something that cannot be done in my case.

Any thoughts? Thanks in advance.