In addition, don’t forget the following (easy to miss when playing a completely different system like Torchbearer):
To help, the players must actually describe what their characters are doing, not simply state “I help using my ‘X’ skill.” (p. 66)
As a follow-up to the above, it’s sometimes (perhaps often?) a good idea to not let the helpers over-describe. It can slow the pace of the game a bit, especially during really “crunchy” bits, such as during Conflicts.
Don’t forget the You Reap What You Sow rule (p. 66) – everyone who donates a die of help for a test is bound by the results of the roll.
Help Checks (p. 23) might be what you were thinking of. If you choose to spend a check when you help another character (assuming you have checks to burn), you get to mark a Pass or Fail for the test, as if you were the one making the roll. You are not required to spend this check – only if you want to leech off your companions’ successes and failures. And, of course, all other rules for Help still apply.