That is not as canon as the galaxy 1,000 people, I always thought it was 750. Also there is no rule saying a LCDR can’t take command of 900 people. And also I did not mean command of the ship but lead of the mission. We have seen this before during TNG. Now while that was an admiral who lead the mission that’s just because Picard was a 4 pip captain. I just rewatched the part where Sisko on the bridge and by the dialogue he is leading the mission since he gave the ships captain the order to engage the tractor beam pretty sternly and he was he one ordering the scientist to turn around the shuttle Also I never said command I said lead of the mission. And by the way a captains orders can be over ruled by a higher ranking officer is some situation. This happens in the Galileo 7 where a government official orders Kirk to abandon search of his crew. Or in Pegasus when rear admiral Pressman tried to take o command of the enterprise. Now while pressman was dirty and it didn’t work, if it was done by another admiral, that admiral would be able to take command.A Nebula class is supposed to have a crew of 900.
Except Sisko doesn't take command, nor could he. An officer can't overrule a ship's captain while aboard his/her ship, even if the visiting officer outranks the captain. Even admirals have to respect a captain's command while aboard their ship.