Need suggestion/help to create the payables approvals

Summary:

Requirement as below
1)There are 3 groups - 25K_GROUP,25Kto500K_GROUP, MORETHAN500K_GROUP
A)Invoice less than 25000 should be approved by group:25L_GROUP (it consists of 4 members/users and one of them should approve it, but the notification should be send for four of them)
B) Invoice amount in between 25000 to 500000 then it should go to the approver group 25Kto500K_GROUP where it consists of 3 members. So, first the invoice should go to approve for the member in the 25K_GROUP (one of them should approve) then it should go to the second approver group 25Kto500K_GROUP where one of them should approve it.