Prevent drop on specific nodes and allow drop on specific nodes

[ParsaJR]

Hello. I want to implement a functionality in such a way that prevent some draggable nodes to drop in some places & vice versa. Is this controllable in this module? how? With 'on-move','on-change'...etc events I didn't understand how I can control issues like this... returning false in OnMove function does a lot of job for this kind of logic, but it's not working. i don't know why.
If it helps in understanding the problem , My scenario is like this : 'There is 4 number which the user places mathematical symbols between the numbers. And obviously , mathematical symbols should not be placed after or before the whole expression and etc'
What I have implemented now is this 👇

I don't know how to implement such a logic in this module (vue draggable plus). any ideas?