Are some particular friends or all friends has such power?
I have not paid attention on this. But I don't feel this has strong effect. Sometimes several friends attend my match and arrive one by one. I should have suffered big losses in such occasions.
Only seems to happen the first 2-3 friends. Once you got the full 15% possession bonus it isn't an issue.
FC Loella. Server 121. Level 22
14 League Titles
3 Champions Leagues
1 Cup