Vellum Grains two part Sim

[Jwrecks]

Hi everyone.

I'm new to Houdini and getting into Vellum and simulations. 

My question is what would be the best approach to have

Grains Object 01 simulate, be active and be affected by gravity, collide with Grains object 02 at 24 frames in and in time lets say 72 frames have Grains object 02 become active and be affected by gravity?

At the Moment I have a simple growth system spreading with an attribute transfer in a SOP SOLVER in DOPS over object 01.

It works. Within 24 frames object 01 will be affected by gravity an it will collide with Object 02. But I want Object 02 to hold still until a later frame and then becomes active.

I  also have an Attribute  Wrangle running over object 02 @active = 0; which holds but how do I activate it later in time? 

I tried 

if (@Frame > 72){

 @stopped = !@active; 

}

But no dice. 

If someone could help me this would be much appreciated.

I have attached a hip file. 

2ActiveSims_00.hiplc

Edited June 28, 2019 by Jwrecks
Misspellings and Bad VEX