Opennmt-tf update vocab

I am finetuning a model by using update vocab commandline in opennmt-tf latest version, as it is giving me an error that the command does not exist
command line
!onmt-update-vocab --model_dir=/content/drive/MyDrive/Data/English-Tamil/en-kn/run/avg --output_dir=/content/drive/MyDrive/Data/English-Tamil/en-kn/run/eval/new --src_vocab=/content/drive/MyDrive/Data/English-Tamil/en-kn/vocab.SRC --tgt_vocab=/content/drive/MyDrive/Data/English-Tamil/en-kn/vocab.TGT --new_src_vocab /content/drive/MyDrive/Data/english-lambani/vocab.src --new_tgt_vocab /content/drive/MyDrive/Data/english-lambani/vocab.tgt --mode replace
also, when i try to train the model it is giving me unrecognized arguments: --checkpoint_path
the entire command line:
!onmt-main --model_type Transformer --config data.yaml --auto_config train --with_eval --checkpoint_path /content/drive/MyDrive/Data/English-Tamil/en-kn/run/avg --continue_from_checkpoint

onmt-main has a subcommand to update the vocabularies. See the help outputs:

onmt-main -h
onmt-main update_vocab -h

Thank i was able to update the vocab and i am getting a ckpt-0.index and whereas i already have the averaged checkpoint of the previous trained model.

So i am confused which checkpoint to use to train new data for domain adaptation
Thank you