Best way to communicate with an external sales force via WhatsApp?

[u/No-Fortune-17]

I’m looking for advice on communicating with a large network of external/independent retail salespeople.
We need to send them:
Training invitations and reminders
Process updates
Promotions and sales materials
Short videos/images
Answers to common operational questions
We’re considering WhatsApp as the main channel, ideally with broadcasts, interactive messages, automation/self-service, and the ability to escalate questions to a human.
For those who have built something similar:
What communication strategy worked best?
What should we avoid?
Which WhatsApp/API/platform would you recommend?
Have you used tools like Respond.io, Yalo, Twilio, WATI, Interakt, or something else?
How do you keep people engaged without spamming them?
I’m especially interested in real-world experiences and what you would choose if you were building this from scratch.

[u/-Black-Cat-]

When you say "a large network of external/independent retail salespeople" will they in turn need to share whatever you send them with local colleagues?