Hi,
if I am correct, when you are talking about your second "Infocube", what you mean is your MPOS (/SAPAPO/MSDP_ADMIN). This is contains an infocube (among other things), but not a standard BW Infocube, and it is created by the system when you create your MPOS and not through RSA1.
Normal process would be roughly as follows:
1- Infocube1 (sales history) and PA, MPOS, PBs... created. In your PA, you need at least a sales history key figure (to receive sales) and a forecast key figure (to store forecast run results)
2- Create CVCs from Infocube1
3- Bring sales history to PA through /SAPAPO/TSCUBE. This step does not affect Infocube1, but overwrites existing sales history in PA.
4.- A forecast run will save forecast values in Planning Area (in liveCache), not in Infocube1.
thanks,
J.