This is simple script based on telethon which can forward messages from multiple channels to your one channel, and you can create multiple rules in config.yml. Requires pyyaml and telethon install from pip3.

example-config.yml

api_id: 111111 # This has to be an integer.
api_hash: '32symbolsstring' # Long 32 characters hash identifier.
session_name: 'session_name' # Session name.

channels:
  - input_channels:
      - 'channel'
      - 'channel'
      - 'channel'
    output_channel: 'channel'
  - input_channels:
      - 'channel'
      - 'channel'
    output_channel: 'channel'

forwardgram.py

#!/usr/bin/python3
from telethon.sync import TelegramClient, events
from telethon.tl.types import InputChannel
import yaml
import sys

def start(config):
  client = TelegramClient(config["session_name"], config["api_id"], config["api_hash"])
  client.start()

  # ice = input channels entities
  ice = []
  # oc = output channels entities
  oce = []
  # cc - channelsConfig
  for index, cc in enumerate(config["channels"]):

    ice.append([])

    if cc["input_channels"] and cc["output_channel"]:
      for d in client.iter_dialogs():
        if d.name in cc["input_channels"]:
          ice[index].append(d.entity.id)
        if d.name == cc["output_channel"]:
          oce.append(InputChannel(d.entity.id, d.entity.access_hash))

      @client.on(events.NewMessage(chats=ice[index]))
#      @client.on(events.NewMessage(chats=cc["input_channels"]))
      async def handler(event, i=index):
        sender = await event.get_sender()
        ec = event
        ec.message.message += "\n\n @" + sender.username
        print(ec)
        await client.send_message(oce[i], ec.message)

  client.run_until_disconnected()

with open("config.yml", 'rb') as f:
  config = yaml.full_load(f)
  start(config)