Mikrotik BGP Aggregate /26-28

Hello,
We have 3x CCR 1036 that has bgp session with a core router and we want to announce 3x /28 from 144.x.x.x/24 in each router and then aggregate them in our core router,
so is it possible that announce prefixes less than /24 in those CCR1036 and then aggregate them in core router in /24 format?
Thank you.

Yes if all router are yours! Because you can use iBGP form 1036 to core and then Core can announce them as /24 with eBGP to upstreams!
Or you can use OSPF in place of iBGP