Hi Vadim,
Always a bit difficult to explain on scn while keeping it brief! 
But needs must. To answer your questions:
PERIODIC data is loaded to MIRV1=V1AV and I do intend to ask the users to select the year in $TIM1$. But I would like the YTD to also be created in V1AV.
V1CV is just a copy of V1AV for a separate set of users (so can be discounted for this discussion; logic is just so whenever a posting happens to V1AV it also happens to V1CV. I should have taken that bit out; I realise now that it is confusing).
Requirement as it stands:
1. when a record comes from base BW, it will be loaded in respective month in BPC cube (standard UI data load package)
2. when ytd_conversion is run, script should post that number to all future months of the year. It should post with reference to the same dimension members
The two problems I am now facing with above script are:
a. The issue with the delta posting rather than a full record. I might have a way around this problem by using MIRV2 as a counter. Still need to test, but then I now have problem b.
b. Since I am passing the $TIM1$ variable, the script posts for all months regardless of the month I would run it in. E.g. if I run in calendar m/o Jan, I want script to post YTD from Jan-Dec. If I run in calendar m/o June, I want script to post YTD from Jun-Dec. Currently, it always runs for the full year. I need to think about adding a variable so TIME can be select input and then run only for remaining months of the year.
My base query though still remains: Is it possible to post with a REC() function, or ALLOCATION() or some other where the signdata appends, rather than overwrites the previous entries? 'Coz that is what seems to be happening regardless of which feature I have used.
regards
shrikant
PS: I have tried with the REC() option also, but rather than add up the numbers, the system still just seems to be posting a delta.