Using a network discovery to add volumes for monitoring

We have hundreds of Agent-polled nodes and I want to add Swap space monitoring for them.
This is important: nodes are already Agent-polled.
Unfortunately, "List Resource" button is hidden if I check several nodes:

This is example of bad UX, where I can't use ordinary feauture without any reason.


Likely, you will suggest me to use Network Discovery, but it doesn't work well.

My step-by-step course of action:

1. Settings > Network Discovery

And the first question: how can I add nodes here automaticly (for example based of NodeRole or NodeOwner custom property)?
I have no list if IP's for my dozens nodes.
Manual filling IP addresses is nonsense. 

2. Next, Next, Next

3. "Manually set up monitoring" (because I don't want to add volumes other than Swap space): 

4. Yes, run:

5. Waiting some time

6. Results (5/5 nodes found - I wouldn't have the patience for 250 IP's)

 

And the second question: Why are they "net-snmp - Linux"? They are Agent-polled nodes.

7. I don't need any network interfaces, so ucheck all:

8. Volumes. Let's check only "RAM", because Swap space is in this category.

  

9. Next, Next, Next

10. Results:

Skipped, not processed. That's pretty suspicious, hm?

11. Finish

12. Let's check these 5 nodes, shall we?

First one:

No tick!


Second:

No tick!


Third:

No tick!

...


Fourth:

No tick!


Fifth:

No tick!


So question is the same: how to add volumes for several (dozens/hundreds) nodes simultaneously?