That's an awfully small cage for one lovebird, let alone two lovebirds. And definitely cannot put a Quaker in that one...That cage looks to be the correct size for maybe a single American Budgie, that's about it. Way too small for two lovebirds. You could use it as a very temporary solution until you can pick-up an appropriate cage for them, but not for long. You have to remember that it's not good enough that they can both just open their wings up the whole way, because that would be about all the two of them could do inside of that cage. And you could only at most get maybe 1-2 toys in there with them, which would greatly inhibit their ability to move around and play, and they should be able to have 5-6 toys in the cage with them at any given time. So there's just no way that this cage would work for two lovebirds long-term.
I'd get onto your local Craigslist, there are usually tons of medium to large to extra-large bird cages all over Craigslist, and they're usually really cheap because people just want to get rid of them for the space. I'd see what you can find there, and when you find one (say you find a really great deal on a really large cage) then consider which cage at that point is better for the two lovebirds and which for the Quaker. Obviously the Quaker needs a pretty large cage, so just look at each cage and go from there. Either way though, this cage is at best a travel-cage...
