The bonding guide below explains the whole process.
Provided both the sows are not babies (babies need to be bonded immediately), you would do best to have them live in separate but side by side cages for a few days before you attempt a neutral territory bonding. This can help them both settle and get used to each other. You may see fear aggression issues if you try to bond them too soon and if they are both on edge.
While bonding teen boars can be tricky (not impossible), it’s not necessarily the case for sows. They don’t have to be past their teens to be more likely to be successful (neither do boars though), as sows are wired to live in herds. What can happen though is that the older the sow the less willing they can be to accept a change, so bonding older sows can be trickier. Bonding two adult sows is not always plain sailing - you say you think your sow will want to establish dominance. Do you know anything about the new sow? If she is also dominant, then usually sows are not willing to give up their position. Whereas boars tend to mellow out with age, sows don’t.
A full on fight is less likely to occur when a bond fails when bonding sows, the signs of failure can be different.
The area needs to be neutral but there should not be any hides in the bonding pen at all.
Only give them hides once you feel they are ready to move them back into a cage.
The full bonding process takes two weeks, and it can still fail during this time even if they initially accept each other.
While you can follow the guide - neutral territory etx - the rest is down to the piggies and whether thry are going to like each other - they are either going to be compatible or they won’t. Make sure you have a back up plan.
Bonding and Interaction: Illustrated social behaviours and bonding dynamics
This guide also has a section on bonding sows
Sows: Behaviour and female health problems (including ovarian cysts)
Sows: Behaviour and female health problems (including ovarian cysts)