[C&K]

I can understand wanting to know if the two of them well get along, but you are putting Chewie at risk by introducing him to a shelter animal. You can call the shelter and ask about certain things, they may be a great shelter, and if he is separate from other guineas, and has been there 3 weeks with no problems, then the risk may be very low. In a perfect situation, you would bring Bacon home or to a friend or relatives, wait 3 weeks and then introduce him to Chewie. I would think long and hard about the benifits and risks of doing this. Last thing you need is another guinea ganging up on Chewie, however you don't want his health to be the price of premature introductions.

If you do introduce them, then I would qarentine them together afterwards. Maybe it would help if they spent 3 weeks together and then met the rest of the crew... May feel like they have a friend in the park...

Honestly I am not sure what I would do in your situation... Maybe adopt him and quarentene him separately, then introduce him to Chewie, if they don't get along after a week or two, look at rehoming Bacon yourself?

Generally the only place where it is really safe to introduce a new pig to match for personality is at a reputable rescuer...