How to configure join methods in sequelize

Question

Say I have users and projects. Than I create a 1: m connection between them.

const User = sequlize.define("user", {...})
const Project = sequelize.define("project". {...})

User.hasMany(Project, { as: "projects" })

The farther secelize creates

addProject 

for me automatically.

In other scenarios, I might need a custom function.

For example, I can check if this user of the project is allowed.

In other scenarios, I may also need to prevent the continuation of adding these association methods to my object.

My questions:

• Is there a way to create a custom association method, if not, can I at least define a verification method?

• Can I prevent the use of secelize to add a specific association method?