What is the relationship among the three brands: eWeLink, Sonoff and Eachen? Are they affiliated with each other or do they belong to the same company and simply operate in different areas? Official information is difficult to find.
About CoolKit and eWeLink
CoolKit technology is the company’s name, eWeLink is our solution’s name and the name of the smart home platform, CoolKit offers Smart Home IoT Solutions to traditional manufacturers, like OEM partner SONOFF.
All eWeLink Support devices can connect and work with Google Assistant, Amazon Alexa, Yandex Alice, AliGenie, DuerOS, Mi Home, IFTTT, and many other platforms. eWeLink is also recognized by Google as an Authorized Smart Home Solution Provider(Business Resources | Google Home Developers), and Smart Home IoT Solution partner by Amazon Alexa(Works with Alexa IoT Solution Providers | Alexa Skills Kit).
About SONOFF
SONOFF is a smart home Brand committed to offering a complete set of products for electronic enthusiasts with DIY interests. SONOFF provides affordable and reliable smart home products for thousands of homes and offices to lead a carefree life by remotely controlling household appliances and devices from anywhere in the world at any time.
We shipped nearly 5 million products with various categories to our customers globally and helped over 15 million users live in smarter homes than ever.
Our commission is to bring smart and simple life to everyone with ease, making your home alive.
I think Eachan is also a OEM partner of eWeLink, i don’t recognize quite well myself.
Additional, eWeLink don’t make our own product nor the sale any of them, just offer the solutions to help the OME partners to make their devices with less time, less investment in different areas with complexity, etc, and eventually to launch more and more great products with affordable price.
Thanks.
Always 
I will lock this topic to disable further posts and keep it opened to all.