This is just a a quick put-together to check out my curiosity if it might be easy to make em' or not. They won't be as straight forward as the following put-together but it will be somewhat like what you're gonna see. :D
Here's a quick bash on what can connect easily. If I were to go with this configuration, I just need to make one of the GN Fangs sit on the shield, however I think I better not and go with how I intended it by adding an extra connection. I think it is quite possible, just that I need to make sure it will be strong enough.
Hm, maybe I can use the "wings" from the Reborns to use as a base for the Thunder Gundam's wings. Well, that's what I'm thinking for the time being.