(Mark sidles up to the water cooler in the middle of the conversation and says):
MDL, I certainly don't think you did anything wrong under the circumstances, however in future you may find that you see the buoyancy problem earlier, before it got out of hand as it did in this situation. It is very predictable that an inexperienced diver ascending from a deep dive will experience buoyancy changes grater than those that they are used to, so should be watched.
Without knowing what computer you have, it is hard to judge what the "green and yellow areas" really mean, or how close you were to NDL's.
I personally think in this situation it would have been acceptable to descend to complete the safety stop unless some other factor was involved as seems to be in this case (surface current and a hard swim to the descent line).
I think, considering your role as the more experienced diver here, your decision to surface with her was the correct one. I personally have dragged people back down to 30 ft deco stops when they have accidentally broken a deco ceiling and hit the surface.
Ultimately, only you know the criteria you used to decide whether the "less experienced" diver was qualified to make this dive, but you decided that it was OK, and we all have to go through the learning curve and mentoring from more experienced divers is one of the best ways to progress in diving.
When confronted with this type of decision, there are two ways you can Analise it:
1) if all goes according to plan, we should be able to manage it and everything should be OK.
2) if you suddenly have to deal with Sudden, High Intensisty Training, and we will still be able to deal with it then everything should be OK.
If you chose door number one, then you will eventually run into trouble
If you choose door number 2, then when Mr Murphy comes along to mess everything up, you will be ready to deal with the situation.
