How do I tame two bonded conures?

by Shelby
(Ohio)

I foster for a local parrot rescue group, and I have recently brought in two conures (one sun male, and one jenday female). they are extremely bonded. Neither will step up onto my hand from in the cage, on the cage, ect. The female is very fearful. She runs away from me, always hissing, and the male does the same until I can get him away from her, where he then turns into a sweetheart (except for the screaming back to her).

I need to get these two friendly and tame so they can be adopted out to a family, but I'm not sure how I can get them to do it without splitting them up (and if I do that then they will scream and I live in an apartment with not very nice neighbors).

I know this behavior is not medical as they just returned from the avian vet. so any suggestions would be greatly appreciated!!
(sorry it was long ha)