So here's the scenario,

Player A has the Crown Regent

Player B has Lord Commander of the Kingsguard

Player C has Master of Whispers

Player "A" attacks player "C" with a military challenge and its unopposed. Then player "B" redirects it to himself. Can player "A" then use his title to redirect the challenge back to the original target?

thanks in advance.

Tim

From the Core Set Rules:

Crown Regent

This title also has a special ability that allows you to redirect one challenge each
round. 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.

So, you can only use Crown Regent immediately after the challenge is initiated. By the time Lord Commander redirects based on the original defender's failure to declare defenders, you are waaay beyond the point of initiating the challenge and declaring attackers. So by the time Lord Commander is involved, Crown Regent has blown his opportunity.