Pytorch Lightning cli : modify callback

I use lightning cli with a config file :

config file :

**callbacks:**
**  - class_path: pytorch_lightning.callbacks.ModelCheckpoint**
**    init_args:**
**      save_top_k: 1**
**      filename: "best"**
**      save_last: true**
**      monitor: my_metric**
**      verbose: true**
**      save_on_train_epoch_end: true**
**      every_n_epochs: 30**
**      mode: max**
**      save_weights_only: false**

**  - class_path: pytorch_lightning.callbacks.LearningRateMonitor**
**  - class_path: pytorch_lightning.callbacks.RichProgressBar**

I would like to modify ModelCheckpoint.init_args.every_n_epoch but I have only access to the cli command line. How I am supposed to do it?

Thanks

Remi