Uses Telethon to create a Telegram Client and forward messages silently from any entities (Channels, Groups or Users) to any other entities.

TelegramForwarder.py

from telethon import TelegramClient, events

#/////
# Get list of ids from the "Dialogos" list printed after logging
entity_ids = []
to_ids = []

# Register an APP in https://my.telegram.org/
api_id = 0
api_hash = ""
#/////

client = TelegramClient('session_name', api_id, api_hash, update_workers=1, spawn_read_thread=False)
client.start()

print("Dialogs:")
dialogs = client.get_dialogs()
for d in dialogs:
  print("\t", d.title, ":", d.entity.id)

if len(entity_ids) == 0:
  print("Remember to set the 'entity' and 'to' ids. Check the dialog list.")

@client.on(events.NewMessage)
def newMessage(event):
  if (event.chat.id in entity_ids):
    for eid in to_ids:
      entity = client.get_input_entity(eid)
      client.send_message(entity, event.raw_text)

client.idle()