Crown Regent - After a player initiates a challenge and declares a target and attackers, you may use this title to make that player choose a new target for the attack. That player must choose a legal target. If there are no other legal targets, the attack goes through against the original target. Players can never choose to attack themselves

Lord Commander of the Kingsguard - When an opponent is attacked by another opponent in a (Military) challenge and decides not to declare any defenders, you can use this title to change the target of the attack. The attacker cannot back out of the challenge, and any characters he declared as attackers against the original opponent are now attacking you. If you win the challenge, you move one power from the attacker’s House to your own. Be careful, though, because if you lose the challenge you will have to satisfy the attacker’s claim. If, for any reason, you are not a legal target for the declared attack, you cannot use thisability to redirect the challenge

Crown Regent is a cancel that occurs immediately after attackers are knelt. Lord Commander is a cancel that occurs immediately after the defender declares no defenders.

So, the scenario you propose can't happen. By the time the Lord Commander is eligible to redirect, it is way past the window for the Crown Regent.

The second scenario, on the other hand is very possible due to the timing previously outlined.

So where in the challenges phase structure does each interaction happen (both are triggered responses, passives or what designation in relation to using the Title action)

When Lord Commander redirects where in turn structure does the action return? Does the attacker get the chance to declare stealth? Are Player Actions available after either/both target changes? Both effects must change the current position on the Phase.

My friend was arguing that the "The attacker cannot back out of the challenge" part of the Lord Commander wording means that you can not redirect the battle again, I don't believe this wording is meant to be a limiter on redirects.

A challenge goes like this:

1) Declare challenge: choose defending player, challenge type, declare and kneel attackers

2) Actions

3) Declare defenders: attacker chooses stealth targets, defending player declares and kneels defenders

4) Actions

5) Resolve challenge: determine winner, implement claim (if attacker won), award unpposed (if applicable), award Renown

Crown Regent (which is not a cancel) can be used in step 1. Lord Commander of the Kingsguard is a cancel for step 3 and makes the game go back to step 2 (but not step 1, so Crown Regent cannot be used - and there is no way to change which characters attack). The Support mechanic also works at step 3, but since it is not a cancel, the Lord Commander gets the first opportunity to act.

Here is the ruling from FFG

"The redirect ability on Lord Commander of the Kingsguard occurs during step 2 (save/cancel) of the resolution of the Framework Action Window in which stealth targets are chosen and defenders are (not) declared. It cancels the initiation of this Window, and re-opens the Player Action Window between declaring attackers (now against the new target) and assigning stealth."

I really wish they would have this info in the FAQ so it is easily locatable if Small Council is going to be used in official tournaments.

I am looking for something that indicates specifically that the Crown Regent activates in Step 1 instead of Step 2 (after attack is declared, before any defenders are declared) It seems like this would be a player action taken in Step 2

The ruling about the Lord Commander of the Kingsguard is in the FAQ. It is just before the restricted lists.

The Crown Regent's redirection is an (optional) passive effect that gets off a challenge being declared, so it happens in Step 4 of the "Declare Challenge" Framework Action Window. It isn't a player action, because the definition doesn't specify a "Challenges:" effect (note that it can be used in any phase) or "as a player action" (like the Naval mechanic does).