Why does a group not inherit successfully from pop

[leesanghyeok]

I want to make fireworks using pop network in houdini.

So I made particles that go up. It is  calculated in "popreplicate1" 

And I wanted to make particles that come out when source particles are dead.

So I made a group named "dead" and replicate a dead group.

 

This node structure runs well (I forgot merging)

But this node structure is not working properly I think the problem is that the group has a problem as the stream has changed.

 

After completing the operation at the first input of merge, do we continue to use the stream of the first input when moving on to the second input?

 

I want to know what the problem is.