Sorry for being a little nosy, but this is not necessary. If you have a product that feel is excellent, you can make an announcement and lure people to use it through other ways instead of campaign inside some other service's thread. Not cool.

Imagine you make an announcement and about 10 other services just come under your thread, telling people to instead sign up for their services. How would you feel as the owner of the announcement?
It's like Pepsi making a billboard and the Coca-Cola also comes and slaps their banner right on top