Possible yes, good idea no. I actually tried this exact thing with my first Reef tank. I was going to culture a couple of frags for my DT and grow a little bit of macro in there to deal with nitrates. The problem is it's hard to maintain a working refugium around a bunch of coral frags so eventually you have to pick between the macro and the corals. In my case, the macro killed the corals so I just kept the macro till a couple months ago and rearranged the tank into a dedicated coral tank with frag rack sideline. Also, as mentioned corals need more low spectrum light and macros need more high spectrum light, so finding a decent lighting balance would be a chore.