Hello!

coul anyone suggest me a good mod for having multiple followers?

I'm still playing on the 11.11.11 version of Skyrim (plus dlcs and updates!), I'm already using skse, so there shouldn't be limitations...

http://www.nexusmods.com/skyrim/mods/15524/? + http://www.nexusmods.com/skyrim/mods/71022/? comes first to my mind. There's also http://www.nexusmods.com/skyrim/mods/12933/? but I haven't used it.

There are a few choices for multiple individual followers, but I don't recall any mods that provide multiple interacting followers. Vilja has code to notice certain other followers, and there may be more that do the same, but that's not quite the same as a combo from a single author.

You can have more than one if you take certain paths in the unmodded game. Serana +1 is possible if you park your current follower at the right time. However, they will each act as if the other is not present.