If you haven't repotted the smaller one, you may wish to do that. Give the roots a good inspection and with a sterile cutter, clip the rotten roots. You may want to presoak the new medium to allow it to absorb moisture since it usually will not readily absorb water. The best way to do this with bark is the day before repotting, soak the bark overnight in a bowl with very warm/hot water. This opens the pores on the bark so it can absorb some water.
I made the mistake of not doing this and my phal started to be underwatered. I was mystified until a grower showed me the error of my ways. I now always keep a baggie with moistened bark at the ready in the event I have a potting emergency.
Keep us posted on the Phal's progress.
Link to set of instructions:
LINK