JSON integration: Room architecture (many-to-many) with Relation, Embedded or TypeConverter?

I am looking to find the most efficient way to use this kind of data:

I have the following JSON (simplified for the example):

{
  "organizations": [{
      "id": 1,
      "name": "Orga One"
    },
    {
      "id": 2,
      "name": "Orga Two"
    }],
    "forms": [{
      "id": 10,
      "name": "Form 10",
      "organizationsId": [
        1,
        2
        ]
    },
    {
      "id": 11,
      "name": "Form 11",
      "organizationsId": [
        2
        ]
    }
    ]
}

Here my entities

@Entity
class Organization(
        @PrimaryKey
        val id: Int,
        val name: String?
)

@Entity
class Form(
        @PrimaryKey
        val id: Int,
        val name: String,
        @Ignore
        val organizationsId: List<Int>
)

@Entity(foreignKeys = [ForeignKey(entity = Organization::class, parentColumns = ["id"], childColumns = ["orga_id"]), ForeignKey(entity = Form::class, parentColumns = ["id"], childColumns = ["form_id"])])
class OrganizationForm(
        @ColumnInfo(name = "orga_id")
        val orgaId: Int,
        @ColumnInfo(name = "form_id")
        val formId: Int
)

//And the POJO
class FormOrganization(
        @ColumnInfo(name = "orga_id")
        val organizationId: Int,
        val id: Int,
        val name: String?
)

I would like to integrate this data easily in my Room database, I will need to query for a form and an organization independently so I will have two tables (and there are lots of data in the form object).

In the end, I want to be able to find all forms with organizationId = 2 ? Like, fun findAllFormsWithOrganizationId(id: Int): LiveData<List<OrgaForms>>

I was looking to create a Pojo as an intermediate that will hold the information of organization and forms.. But I wasn't able to make it works...