Analytics Software

Here's the background, hopefully I can convey clearly:

We are in the middle of a HP implementation, with our primary data source being an HFM database. This HFM database holds fairly detail level of accounts due to the fact we have never had an Essbase or other technology people can do analytics off of. Primary focus of first phase of the HP project is to do planning, forecasting, and allocating of the dataset from HFM, but at a higher level. So, for example if 20 accounts today roll under 'Travel', we want to plan/forecast/allocate at the 'Travel' level, not the 20 accounts. So...

We do not have any sort of data warehouse or finance data mart, or whatever you want to call it. All of our data, as stated above, sits in HFM today and will be for the foreseeable future (125+ different ledger feeds coming through FDM today to feed HFM). We intend on using an Extended Analytics HFM extract to populate to a SQL staging databases of sorts. The next step is where my question lies. i am proposing we stick an Essbase ASO cube in the middle, which is for the most part, a replica of the HFM structure (minus a few dimensions we don't need). From there, I would push the data required to the Planning BSO cube at a much higher level. What i am trying to understand is how partitions can work between these cubes. Keeping in mind the BSO cube is a Planning cube, and the ASO cube is Essbase only. The user requirements are:

1) Users will Plan/Forecast/Allocate in BSO cube at higher level ('Travel') for example
2) When analyzing data in BSO cube in SmartView, if they click on the 'Travel' cell, it should "drill" into the detail sitting in the ASO cube automatically
3) The budget/forecast data in the BSO cube should populate back into the ASO cube at the higher level

So, it seems to me we almost have a need for a two-way partition. The BSO cube needs a partition to the ASO cube for detailed actuals, and the ASO cube needs a partition to the BSO cube for the Plan and Forecast data.

Additionally, looking for options on how to load the data from the SQL database to the ASO cube (FDM, load rules, etc...); and no we did not buy Hyperroll (EAL)

Looking for advice or other experiences. I am relatively new to Essbase, so I hope I have stated the question/issue clearly. Thanks for your responses.