dnd 3.5e: What movement limits exist when maintaining a claw?

When the grappler tries to keep the grapple (PH 156), how much movement can the grappler take to move to the target space?

The comments say that this problem apparently is not resolved in D & D 3.5Different discussions about grappling. (Seriously, I could not find anything either, that's why I asked). If there is no original answer, here is an alternative.

If the rules keep silent about this, what is a good rule of the house for the movement that the grappler can take to move towards the target space when the grappler tries to keep the grapple (PH 156)?

Yesterday night the thief ("A rogue is just a pretentious thief ") was attacked by an advanced giant cockroach (Und 87-8), whose space is 10 feet x 10 feet and whose reach is 5 feet. Adjacent to the giant cockroach is an advanced unfriendly ripper (Ci 131-2). The map looked like this:

---- CC ---- All 4 Cs = 1 giant cockroach
---- CCR --- R is the hostile ripper
------ T --- T is the thief

The giant cockroach started a claw. versus the thief. She had exhausted her attacks of opportunity. The giant cockroach managed to grab her with his touch of attack. The giant cockroach won the opposite check, inflicting its unarmed attack damage (which was a small die because the giant cockroach lacked monk levels, but a big advantage, since giant cockroaches have impressive Force scores, who knew? ). Then it was time for the giant cockroach to keep the claw.

Starting a Grapple under the heading Step 4: Keep Grapple (PH 156) reads

To maintain the fight in later rounds, you must move to the target space. (This movement is free and does not count as part of its movement in the round). Moving, as usual, provokes attacks of opportunity from threatening opponents, but not from their objective.

If you can not move to your target space, you can not keep the fight and you must immediately release the target. To fight again, you must start at Step 1.

Special rules of movement under the heading Movement of accidental termination in an illegal space (PH 148-9) reads

Sometimes a character ends his movement as he moves through a space where he is not allowed to stop. When that happens, place your miniature in the last legal position you occupied, or the closest legal position, if there is a closer legal position.

The rules of moving through a square under the heading ending your movement say: "You can not end your movement in the same square as another creature unless you are helpless" (PH 148) "

I know that the Keep a Grapple movement is an exception to the Ending Your Movement rule. That is not a thing. What is one thing is the giant cockroach shortest route to maintain the claw meant occupying the same square as the ripperand that is not legal.

---------- Both cs = 1 giant cockroach
----- CR --- R is the hostile ripper And part of the giant cockroach
----- CT --- T is the thief And part of the giant cockroach

Movement is movement, even if it is free, and while the square occupation is largely eliminated for the fighter and the objective, it is not waived for any other creatures At the table, I ruled that the giant cockroach was forced to return to its last legal position, but I want to make sure. Could the cockroach have taken a different route, maybe even around the battlefield or even the world (perhaps causing opportunity attacks along the way): be in a position to hold the hook instead of taking the shortest route?