I’ve attached the bonding guide and procedure in below. It involves having a completely neutral area to carry out the bonding. (Don’t put macaroon directly into michi’s cage). You will also have to make sure the cage you intend on them living in is completely cleaned down so it doesn’t smell of Michi anymore.
If the new piggy isn’t coming from a rescue centre, then she will need to be quarantined for two weeks ideally in a separate room to ensure no illnesses can be passed to your piggy. Also make sure macaroon sees a vet.
If you are doing the bonding yourself, then do ensure you have a plan b in case the two piggies aren’t compatible and don’t get on.
Bonding and Interaction: Illustrated social behaviours and bonding dynamics
Dominance Behaviours In Guinea Pigs
Sows: Behaviour and female health problems (including ovarian cysts)