Advice needed on introducing guinea pigs

[kiemariex]

Hey everyone!
I am new to owning guinea pigs but I am already in love! I have a baby who is about 3 months old and she came with an eye infection so I wanted to get her a friend after I had finished the medicine process. I finally finished a couple days ago and she seems to be doing well.
I decided it was time to get her a friend since guinea pigs are social animals, however ive seen some different ideas and ways to introduce them. Currently, I have them in separate cages right next to each other (by the way the one I got is a little older, she’s about five months). I then left my sister to watch them as I set up the new ones separate cage and she let them kind of i tropics themselves. When I came in to ask what she was doing she said that they were fine and nothing was wrong. My New Guinea then bit (?) my baby guinea or tried to snip at her. My New Guinea freaked out and wouldn’t let anyone else touch her but me and she even tried to hit my boyfriend and she has never shown signs of aggression. I know to never introduce them the first week but my sister didn’t. I’m worried my baby is now going to be aggressive and won’t like the other guinea at all.
I don’t know what to do and I feel like I messed everything up. Does anyone have any advice?

 

[Siikibam]

She probably feels her territory was invaded by the new pig. Introductions should be on neutral ground. So set up a play pen or something similar with just a pile of hay. You have to see it through to the end whatever the outcome. Have a read of the links below.
Sows: Behaviour and female health problems (including ovarian cysts)
Bonding and Interaction: Illustrated social behaviours and bonding dynamics
Dominance Behaviours In Guinea Pigs

Character compatibility is more important than age.

 

[Piggies&buns]

Let things calm down and then try a correct neutral territory introduction. The guides linked in above tell you how to do it.
It’s important to understand the social dynamics of piggies and know what behaviours you are looking out for. Character compatibility is the most important factor, and bonding is not a straight forward exercise as you can’t predict whether two piggies are going to like each other and have a successful bond