Need to fetch Transaction approver start date and the next level approver details

Summary:

We have a requirement to fetch the date the transaction was assigned to each level of approver and also the next level approver details. This is applicable for all transactions

Content (please ensure you mask any confidential information):

Transaction have multiple levels of approval, 
we are only able to retrieve information about past and current approvers from the workflow and BPM tables history tables. 
However, we are unable to obtain details about future approvers. 

Also, FND_BPM_TASK_HISTORY_B table contain same initiation date for different approvers(at different levels) for a particular transaction. The completion date reflects the actual completion date by each approver for that transaction.