Should I tell

Two years ago my dad told me that on of my friends might be my little sister. Him and my step mom wanted to get a DNA test done but her mom would not alow it. But I strongly believe that she is my sister because she looks like my older sister and my aunt. No one wants to tell her but I do. Sooner or later she will find out. And I am afraid that when she does she will want nothing do to with me because i could have told her and didn't.

But i know i am not wrong because she looks so much like me sister and my aunt. she looks nothing like her mom or the guy that her mom told her was her dad.
but they can not do the DNA test without her mom knowing because my sister is 5 years younger then me so therefore she is still a minor. and her mom has to make the disission.

I had a friend in high school, we are spitting images of one another, we are not related. I think this is something best handled by your father, even if you have to wait until she is old enough to take the test of her own accord. The adults made the situation, let them be the ones to fix it and you just be her friend and then maybe one day her sister if it turns out to be the truth.

No.
if she finds out, she will not necessarily say "why did you not tell me? you knew, and you didn't tell me." because nobody properly knew.
it is not upto you to break news to her that you don't know is true, it could be a coincidence, and if it is not, she can find out by herself.
that way, you won't be up for blame if she starts to lash out at random people.

You should tell her

Dont tell her yet coz u r not sure. If u r right and she finds out then pretend u never knew!

Don't tell her.

Don't do it

That is a lot of proof because she looks like NO ONE in her family.

I have heard a lot of different reasons on y to tell her and y not to tell her. i think i have made my dicition on not to tell her and let my dad and her mom tell her. but if they do not tell her before she is 18 i am going to tell her.

My dad has decide not to tell her at all so next time i see her i am going to tell her.

This is a really hard situtaion...maybe you could tell ur friend that she needs to ask her mum some questions about her dad or something i dunno, its really hard coz either way someone will get hurt...
good luck!
if u ever need to talk im here :)