It takes some major event for a unit name change to be authorized and they did participate in Operation Bulldog, the relief force that went to Huntress and they did fight the Ghost Bears on Kiesen and Meilen during the First Combine-Dominion War. So you could put forth a name change for some heroic battle/sacrifice that happened during one of those events.
Possible example: during the Battle on Kiesen a strong Ghost Bear force broke through the ComGuard's lines and were moving on the 31st Division's main supply base. With most of the Division already heavily engaged, Acolyte Jake Hawkins led an ad-hoc ComGuard unit to a mountain pass that the Ghost Bears would have to traverse in order to delay the Ghost Bear long enough for the Division commander to move additional forces into position.
When Precentor Cabral's forces reached the acolyte's position, they were shaken by the incredible devastation they beheld. Acolyte Hawkins' Atlas was the only 'Mech standing in a field littered with shattered 'Mechs and vehicles from both sides. When Hawkins failed to respond, Cabral sent some men to check on him and found that he had bleed out at his controls. No survivors were found among the fallen ComGuards. Hawkins' BattleROM told the story of how he and his men had held the line against the Ghost Bears' furious assault until one by one they started falling until only Hawkins was left. After Hawkins' final salvo decapitated the Ghost Bear commander, the few surviving Ghost Bears withdrew back to their lines. The sacrifice of Hawkins and his men enable the ComGuard and DCMS forces to push the Ghost Bears off-planet.
Precentor Cabral would submit a request to the planetary governor, which was quickly approved, that the bodies of the fallen be buried in the pass where they had laid down their lives. Attendees to the dedication ceremony would later swear that Hawkins' repaired Atlas shed tears during the ceremony. Skeptics attributed it to battle damage but technicians were never able to find a leak.