Approval -Management using Approval Engine

 Experts,
 In my current application i am trying to build a functionality through Administration-approval management.

The process starts with a liability amount. Liability amount is the field in siebel where the user has the abilty to enter the amount. And if the amount is greater than 1 Million, I need to do a hardstop of current policy creation and start a approval process.

If the liabilty amount is > 25 Million, then i need a level 1 approval. In a similar fashion if amount: >50 M then level 2 approval, >100 M then level 3 approval, and >150M then level 4 approval.

Each levels are defined as group users based on position and the state they belong to.