I double-checked my copy of Hardee's, Volume 1. Article 1, Section 12 (Posts of Company Officers, Sergeants and Corporals) states, "The company officers and sergeants are nine in number". That would indicate the captain, three lieutenants and five sergeants. Section 18 gives the 3rd LT's position within the company formation, "The third lieutenant,opposite the centre of the second platoon."

The designation of 1st, 2nd and 3rd Lieutenant indicated the officer's seniority within the company in the same way that the sergeants were designated First through Fifth Sergeant and the corporals were designated First through Eighth Corporal.

In the US service, the 1st Lieutenant was designated by a silver bar on the shoulder straps, while the 2nd and 3rd Lieutenants both had empty shoulder straps. I would assume that the CS service would follow the same rule.

3rd Lieutenants became scarce as the war dragged on. As the companies became smaller due to combat attrition, there was less of a need for as many officers and NCOs as when the ranks were full.