Freela
Senior Guinea Pig
They look like they're doing okay... those are normal dominance behaviors, your older pig wants to be sure the younger pig knows that she is lower on the hierarchy. If you want them to eventually share a pen/cage, I would give them time to work through their dominance issues in a neutral setting, then scrub down the cage/pen you will be using (to remove any scent marks from the pig already living there) and move them in together. Putting them together and taking them apart can be more stressful for them (and you), as they have to resort the dominance issues all over every single time they meet. Guinea pigs don't really understand the concepts of 'dates' to get to know each other... to them, you meet a new pig, you are assessing them for inclusion or exclusion in the group every time.