I would think it also depends on the language of the trust that was created for BK prior to WH's death. If I remember correctly, BK was to get certain assets when she turned 21, 25 and 30. There is likely language within the trust document which states what is to occur if the trust fails (i.e. there is no longer an ascertainable beneficiary if she passes). It is possible, due to a failure of the trust, that all the assets will go back to WH's estate, and then follow the lines of succession making it possible that the assets would go to WH's mother and/or siblings. I would guess that what has already been distributed (meaning it is BK's property/asset only and not in the trust) would go to BB. Anything undistributed would go back to WH's estate as there is no longer a beneficiary?
All MOO.