How can I create a new record, whilst also storing its related entities without creating a new record for the related entities (THEY ALREADY EXIST).

Here is how I make a room furniture item. I don’t want to create a FurnitureItem because that already exists. If I assign it, EF tries to create it. If I don’t assign it, it says it cannot be null.

var roomFurnitureItem = new RoomFurnitureItem
{
    RoomId = room.Id,
    OwnerId = player.Id,
    OwnerUsername = player.Username,
    FurnitureItem = null,
    PositionX = 0,
    PositionY = 0,
    PositionZ = 0,
    WallPosition = wallPosition,
    Direction = 0,
    LimitedData = playerItem.LimitedData,
    MetaData = playerItem.MetaData,
    CreatedAt = DateTime.Now
};

dbContext.RoomFurnitureItems.Add(roomFurnitureItem);
await dbContext.SaveChangesAsync();

Thanks