Okay, orchid #1 may have lost it's leaves because it had root rot, which is from over watering. Orchids have unique roots that need to have a chance to dry out, other wise they will rot, which goes with the saying, "If in doubt, go without!" Orchids will die faster from over watering than under watering. The best suggestion I have for you is to go to your locale library and rent a few books on orchids, that will also help to identify your plants so you can learn what they need to thrive.

Pitch # 1, it will just frustrate you and even if you are lucky and get it to recover, you probably won't get blooms for 2-3 years.

Yes, there are special fertilizers for orchids, but for a single orchid I'd say go ahead and use the MG. Just use it at @ 1/2 or 1/4 recommended strength weekly or at every watering if you water the remaining orchid less than once a week.

Be sure to let the orchids dry out between waterings as mentioned by the previous poster.

Good luck,

Bob