I would go into the refugium from the DT then to the main sump. You could go with a pipe off the sump or an overflow box going into the next sump. You really don’t need an overflow box. Just a bulk head by the top of the tank with PVC and a 90.
You would need a pretty good size pump to run all that. It might be better to have two pumps. I would split the return line one to each tank then have the overflows go into the same first sump. probably have a 2nd pump running the manifold.
You would want to make sure that the DT tanks won’t over fill the sump since you will have two of them. I’m sure there are other ways to run a set up like that. Hopefully other people will chime in with their thoughts.
You would have to figure out how much flow you need total but my guess is that pump will be more then enough. You’ll have to drill the sump to feed that pump because it’s external.
I have never used zeovit but I think you need to run 10x flow for that system. You have to take head loss into account and your hose or piping. You would also have to look at how much flow each item you want to run off the manifold is going to need. As far as the manifold each item would have to be dialed in.