While it is tempting to want to get a puppy from one of these "Oooops!" litters ... you need to think about it. No one in their right mind would cross a scent hound -like a beagle, a very active, vocal and driven breed that will follow a scent for miles upon miles... with a Boston Terrier, widely known for breathing and respiratory problems, and luxating patellas (bad knees that pop out of joint). They may be cute - but they could be an owner's worst nightmare in vet costs.
The dogs will exhaust themselves to the point they can't breathe. They can inherit eye issues from both sides, Cherry Eye problems from the Beagle side, and Cataracts are a terrible issue with Bostons. And it gets worse from there ..... But, you need to realize that your Chihuahua may NOT want another dog in your home.
Chi's are very one person type of dogs, they have their favorite person in the family & everybody knows it! They can also be very territorial in their homes, and not social with other breeds of dogs. How is your current dog now out in public around other dogs?
Does she play and interact with your friends and family's dogs? If you watch your dog and see what types of dogs she chooses to hang out with, then you can better choose a dog to be in the house with her. She may like quiet mellow dogs - and be greatly bothered by puppies or hyper dogs.
Or - she may choose to not socialize with other dogs at all, and just want to be with you. Having your current dog be happy with another dog in the home is the difference between peace, quiet and harmony ---- and constant tension, issues and squabbles between the dogs every day. Only if your dog is social and will not mind sharing her owner and her home will this work out well.
Rarely do "only dogs" just like "only children" ever want to SHARE the spotlight or the parent, with ANOTHER. Do NOT get the dog as a companion to your Chi. In all likelihood, your Chi is NOT lonely.
You can certainly take it to a play date or invite some other Chi, or similar size toys over, if you think otherwise. If you get another dog, get the dog for YOU, and be HONEST about that. I would spend time around Bostons & Beagles & see how well she interacts with them at say a dog park or in a dog class.
They may be too rough and/or too large. Beagles can be VERY VOCAL. I do not advocate buying "designer" hybrid "mixes".
I CANNOT call them breeds. (They are not"'fixed" in what is produced or you can expect in temperament or looks). Most of the BYB hanging fancy monikers on the mixes, do so, manipulatively in order to sell crosses you an also find in any shelter for a LOT LE$$.
Rarely (if EVER) are the BYB, breeding top quality or healthy versions of the purebreds, or doing any genetic testing. Frequently, they are cross-breeding two breeds with a number of health problems, which do not magically "DISAPPEAR" by doing a cross-breeding. But they COUNT on you NOT understanding basic genetics, or statistics.
My advice would also be to stick with the breed you know & understand, if you feel YOU'D PERSONALLY like another dog. Your dog may be willing to tolerate another, if brought in as a puppy (from a REPUTABLE breeder) or if you adopt an opposite gender & already fixed dog, she approves of. If it does not work out, in either case - you can return the dog or puppy, to either reputable source.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.