Is adding another guinea pig to a bonded pair a good idea?

Guinea pigs are naturally herd animals. It is actually less natural for them to live in pairs than in larger groups. A trio of piggies will indeed rearrange their hierarchical standings with each other, but this is not at all a bad thing. When they will be getting to know each other, you should expect some dominance challenging and play fighting, but again, all normal. As long as no blood or wounds are visible, no problem. Just make sure you are certain they are all the same gender, you wouldn't want accidents!

Please make sure you research HOW to introduce over neutral territory properly! If you rush an introduction, they will be much more likely to feel defensive and attack. If you know what you're doing, it will go smoothly, good luck :)

No, it's not.

Guinea pigs, are "herd animals". They have their own herds, but they don't take too well to "Imposters" joining their group.

I had a group of 5 males (all brothers been together for 4 years) and introduced a rescue pig (I did the whole process over a 2 month period), and all seemed to be going well - until that is, the "imposter" entered their shed and they were having none of it. Poor chiko got charged at and bitten by my 5 boys that had turned into feckin piranhas. Anyway, out of my lovely bonded 5 boys that I had for 4 years living happily together, I now have one pair, and 3 lone guinea pigs as they always attack each other if their ever reintroduced. Chiko (he's fixed) is now living with my 8 females (lucky lad haha).

Leave them be, if their females you may have a chance but males are extemeley territorial (my boys have a 6ft x 8ft shed to themselves, aswell as a 12ft x 14ft plot of land and they still fought over their space).

If you have a pair of females, usually there is a bit of scuffle at the beginning but eventually things settle down. Watch them closely

If you have a pair of males, it may be more difficult to introduce them so make sure you stretch out the introduction process, but there are many people that have successfully had a trio of males in the past.

Good luck!

I introduced another guinea pig to my pair and they were fine just make sure you introduce them properly. Do it one at a time, not both meeting him / her at the same time as they may gang up on him / her.

It is possible just make sure you research how to do it properly