Hi everyone, I need a sincere advice on this issue.
  I have a friend who confided in me that she's  in love with two friends that refer to themselves as brothers. They've all lived in the same house?(including her) with a guardian. Now they are all grown and working but not living together any more. The two guys have approached her for marriage.She's a bit a confused because she sees them as her brothers and she wouldn't want to hurt them.
  What can I advice her to do?

are they biological brother or not
and the girl will have to choose of course

how can she be in love with them n see them as brothers?
get the story together then we'll see what next to do

They are not biological brothers. They've all lived in the same house under the same guardian.That's why she's seeing them as part of her family.

. . . and she's in love with them?
there's a difference between loving someone as a brother and being in love with the person

It seems the guys are playing a game to see who "Sade like pass." I say this because I assume both men, being men, talk about women and they must have talked about her at some point. The conversation must have went like this:

Segun: I gbadun that baby o.
Emeka: I like her too now.
Segun: Make we see who go get am first.
Emeka: Word!

or
Segun: I gbadun that baby o
Emeka: For real? (thinks to himself, I gotta make a move fast before I carry last)
 
Tell your friend not to fall for it. If she sees them as brothers, then that's what they should be.