Hi hopes this helps you further....
Most of the engineering regiments during WWII had TWO battalions, 1st and 2nd. Each battalion had three companies
1st Bn - A, B and C
2nd Bn - D, E and F
Companies are then broken into platoons, etc. Am attaching the WWII reference sheet on this.
Size of Army Units in WWII.pdf
Typically Headquarters unit was a company, not a platoon. A, B, C, D, E and F were called line companies. Then headquarters would come into play.
Bastard (or independent) engineering units such as the 157th and my dad's unit, the 540th, differed from the typical triangle setup of regular infantry units, for those units were based on THREE's. For example, the 34th Infantry Division had THREE regiments, and then each regiment had three battalions and so on. That was typical.
Proud Daughter of Walter (Monday) Poniedzialek
540th Engineer Combat Regiment, 2833rd Bn, H&S Co, 4th Platoon
There's "No Bridge Too Far"