The description is pretty much it.
We have developed a tool/web interface which allows users to receive and requisition a lot of assetIDs and push them thru a work flow, finally to arrive in GP as a new card. However, sometimes these new asset purchases are just that, an additional purchase line item which belongs on the same asset. Said purchases could reduce or increase the cost basis.
I am aware of: <taCreateAssetPurchase>: https://msdn.microsoft.com/en-us/library/jj902643.aspx
I am also aware of: <taCreateAssetBook>: https://msdn.microsoft.com/en-us/library/jj193300.aspx
... which contains: UpdateIfExists "Do not use 1. taCreateAssetBook does not currently support updates. Update functionality will be added in a future release."
This seems to indicate there may be no way of programatically sending a cost basis and book update to GP? This seems to be what happens when someone does this in GP manually:
1. Enter new asset purchase (which updates the Acqcost)
2. Select the existing Book card and update the costs basis
3. Select "yes" to run depreciation (chose life, etc)
4. GP finds all existing book entries for that asset for each time depreciation has been run and totals them, then creates reversing entries.