Magus Coeruleus said:Stalker0, based on your analyzes, what recommendations would you make if I did not want to force anyone to make a roll or aid another necessarily?
In general, aid is only "necessary" when the person is using a low skill for the challenge. If he's using a skill that's about par with the group, you will only get a small drop in your win rate if he doesn't aid.
If the player chooses not to participate in the skill challenge at all, then check your new party vs the standard. If the rest of the party is average, there's probably nothing that needs to be changed for the challenge. If the new party tends to have a big skill user, you may wish to add +1 to the DC to balance it out.