Get relay's address from within script

[Tiago SR]

Dears,

In ISP I work on there is a central ISC DHCP server, which is relayed (DHCP relay) in each PoP.
I would like to get DHCP relay address from within my "on commit", "on release" and "on expiry" scripts.

I've been searching and looking at "man dhcp-eval", but found no way to get it.
DHCP relays are MikroTik routers and only change they can do to DHCP requests is to add option 82 values, 
but I can't use it to add relay's address, as option 82 is already used for authentication purposes.

If there is no direct way to get relay's address, I was thinking in some way to get source address of DHCP 
request, as I presume they would be the same.

I would appreciate it if you could help me.
Thanks.