Unpooled EX amount based approval

We have a simple requirement for expense approval: Based on submitter, approval should be routed to various supervisors as below

A reports to B reports to C reports to BIGBOSS in Dept1

X reports to Y reports to Z reports to same BIGBOSS in same Dept1

A and X do not have any approval limit, as they are only submitters.

B's approval limit (for Dept1): 500

C's approval limit (for Dept1): 1000

Y's approval limit (for Dept1): 500

Z's approval limit (for Dept1): 1000

BIGBOSS approval limit (for Dept 1): 999999999999

If A submits $750 expense report, it should be routed to B and C and stop.