ORIGINAL: sanderz
is there any bad effects depending on the number of Korps units attached to a HQ
also - is there any penalty to attaching a Korps directly to, say AGN rather than one of AGNs subsidiary HQ
Each commander has ratings and the better commanders can handle more Korps in their Armee HQs, I think there is a list at the back of the manual that shows the commander capabilities. Depends on how many divisions are PZ, or Infantry, but if you exceed the commander rating then you find units will not be able to complete their plotted movements. The distance from the HQ to the Korps counts, but provided your rail net is OK, it shouldn't matter whether Korps are attached to Armee, or Armee Grp level, subject to command rating and OP levels.
Best policy is to set your higher HQs (OKH, AGN,etc.) at a high replacement level, even 100%, you can put damaged units in there to recover to 100% strength, also new units will appear in the higher HQs, sometimes understrength and a high replacement setting gets them up to full power, before you send them out to the fighting Korps HQs.
You should leave some divisions (maybe 1 or 2 of those weaker ones you can't use elsewhere) in your Armee HQs as protection. They will count in the defence odds if your HQ is attacked, otherwise the HQ is defenceless. Also have at least 1 fighter unit in the HQs near the front line, set to CAP, if there is a danger of air attack (AAA support units in the HQ will help, but you will probably want them in your PZ Korps, which will otherwise be a juicy target). Your HQs also represent your airfields and you need to protect them.
The game may look simple and out of date, but when you understand how it works it becomes a very good representation of Grand Strategy on the Eastern Front. I don't think it has been bettered yet, even if other games are more glossy, with a better interface.[:)]