Hi Vadim - attached is the log from me running it in simulation via t-code UJKT. The ONLY thing I changed in the Badi you provided was I only passed in Time member 2012.12 since the logic called will get the prior time member (2012.11) and it all worked.
Next, as you suggested, for the DM prompt, I changed the DIMENSION TIME = %PLAN_TIME_SET% in the Badi
and initiated the DM pkg in PLANNING model, and it worked successfully. I'm now seeing the data pushed in the PLANNING model.
Thanks you so much for your help, it is greatly appreciated!