Snapshot Dependency on Specific P4 Stream

Hi,
 

Our pipeline looks like this:
1. Project “PackageGame” that builds and packages our Unreal Engine project.

2. Project “Steampipe” that uploads the artifact dependency to Steam.

In order to create a chain, we have set up a Steampipe-job that runs nightly. 
It has a snapshot dependency on the packaged Unreal game.
When the nightly Steampipe-job triggers, it automatically triggers a PackageGame-job as part of the chain, and then grabs the dependency.

The problem is that if we want to specifically trigger a specific Perforce stream of “PackageGame”, and then upload that.
Since Steampipe is on a different VCS, there's no way to establish a “part of same chain” sequence.
If Steampipe was on the same VCS, we could easily trigger “Steampipe stream B” which would trigger “PackageGame stream B” as well.

But, since they are part of different VCS projects, I can't find any way of having a snapshot dependency on a specific stream.

Example:

PackageGame has stream main, release, and dev. Different streams have different versions of the game.
Steampipe has stream main. It is always the same tools.
 

I want to set up a Steampipe-job called “Steampipe Release” that grabs a snapshot dependency of “PackageGame dev”.
The only way I've kind of made this work is by making an artifact dependency on a specific branch, and then manually trigger the "PackageGame dev" in combination with a trigger for “Finish build” with that branch.

But that makes things very complicated, and we lose the possibility to run chains in a good way.

Could it be possible to somehow set up a chain with a specific stream?

Thanks in advance,

Linus