Hi,
why you release the SO after 1st approval if you are still waiting for others to approve?
Maybe the good approach can be:
1. Requestor sends the SO for approval to multiple approvers
2. If 1st approver, approve the SO, and you notice that some change needs to be made
3. Requestor should first cancel approval request -> SO will become Open
4. Requestor make the change
5. Requestor repeat step 1 and SO get back to 1st approver for approval.