iproute2 help

I'll try to be as succinct as possible, and will answer questions for more detail, rather than posting a (bigger) wall of text.

Intent: I want to configure iproute2 on Server A such that any connections originating from Server A, destined for Server B, lookup the MGMT network; any connections from B to A should reply via the network they arrived by.

Problem: With my current configuration, connections originating from Server B to server A on OPS appear to reply on MGMT

Current relevant rule I tried to write:

• "from all to 10.11.12.13 iif lo lookup mgmt"

(Googling led me to believe that including the "iif lo" would be interpreted to mean "originating connections", but that's not the behaviour I'm seeing.)

Everything else appears to work; generally, a connection to Server A is replied to via the same network it arrived, the intended behaviour. A rule exists such that queries to DNS and NTP servers lookup mgmt by default, which works.

Any assistance would be appreciated.