Strapi don’t rise all the colleciton’s attributs from relationned obj

Hello fellas,

I got a question about the ORM to get data/object with relation(s). So in my case I got an object which can have children of the same type (collection)

---------collection X---------

ObjectA can have ObjectB as a child. when I ask strapi the ObjectA I get all the properties of the X collection (as expected) but when I look at more close it to the ObjectA attributs, children in particular children’s properties. I got the ObjectB but not all the properties, I mean the relation’s (children) is not there (ObjectA.children[0].children equal to undefined) or just got the ID
Exemple bellow :

const ObjectA = strapi.service.collectionX({id : id}) (id of ObjectA);
const ObjectBfromA = ObjectA.children[0]; // which if ObjectB
console.log(ObjectBfromA); // return undefined 
const ObjectB = strapi.service.collectionX({id : ObjectA.children[0].id}) // work too
console.log(ObjectB.children) // will return ObjectB's children as expected

How can I get children of children ? instead of undefined or most of case the ID
Hopefully I’m enough clear to you