Help with plumbing an existing setup

[ShrimpReefer7]

Hi everyone, I need some advice on my return plumbing.

This is my current return pump plumbing. I'm planning to add a manifold to feed my chiller, but I'm not sure of the best way to do it.

Right now, the return line already has a gate valve. Should I redo this section of the plumbing to make the manifold work properly? Also, my drain line doesn't have a gate valve, is that something I should be concerned about?

Or would it be better to skip the manifold altogether and just run the chiller with a separate dedicated pump?

 

[Saltyreef]

We need a better idea of how this is plumbed already. Bean animal? Durso? A shot of your overflow would be helpful.
I myself would not use any check valves. Its a poor fix for a properly set up return.