how to add a trait without losing previouses?

[ghost]

If I do this it override the previous traits. I want to maintains previous traits and add one custom

    const blockManager = this.editor.Blocks
    const blocks = blockManager.getAll()
    blocks.forEach(block => {
      this.editor.DomComponents.addType(block.id, {
        model: {
          defaults: {
            traits: [
              {
                type: 'text',
                name: 'ref',
                label: 'Ref',
                placeholder: 'Insert ref'
              }]
          }
        }
      })
    })

(I do a forEach to add this trait to all blocks)

I would prefer to use

blocks.forEach(block => {
    block.addTrait({
                type: 'text',
                name: 'ref',
                label: 'Ref',
                placeholder: 'Insert ref'
              });

    })

but I block doesn't have addTrait. component has it but blocks doesn't

[ghost]

achieved by adding trait on block mount. When a block is dragged, it adds ref field

this.editor.on(`component:mount`, model => {
      model.addTrait({
        type: 'text',
        name: 'ref',
        label: 'Ref',
        placeholder: 'Insert ref'
      })
    })