ROS7.2.3 Set bgp-nexthop in ibgp

Hi!
I have ~50 routers with p-t-p links with core routers. All routers configured with iBGP route reflection.
All prefixes are announced to all routers, but they receive as nexthop unreachable IP-address of router instead of IP of core router.
On ROS6 i can use set-out-nexthop filter for set nexthop.
How can i do the same in ROS7 ?

Not sure about route reflection but had a similar iBGP problem and solved it on a connection at “/routing bgp connection” with the option “nexthop-choice=force-self”

http://forum.mikrotik.com/t/ibgp-rr/154769/1