I think you are reading too much in to this @Yaser Als.

When ever I have matches (even when being here in the office), I will call some colleagues to support me. If I'm not at the office I'll text some friends of mine to fire up the game and come watch my match if I didn't notify them before hand.

There are also in-game friends of mine with whom I've played in the same League, CL or Cup competition groups that gradually I befriended along the way and those occasionally pop-up in my supporters list during a live match.

Your opponent just has some friends who either play actively and keep in mind each other's match times or they call for each other. It's not against the rules, it's part of the game.

And keep in mind that there is a "possession bonus" limit of 15% from fans (Other Managers, Stadium Attendance).