A block that consumes steam to power a steam engine (from Create)
Possibly a block (steam valve?) that can be placed on a Create steam boiler to turn steam from that into Systeams steam for powering a steam dynamo.

Looks like this would require mixining into Create, which I am not comfortable doing.
If someone else wants to PR this that would be great, however I will probably be stricter than normal in reviewing that.

I just came to this Github looking to propose this enhancement. Turning Create steam into Systeams steam would be amazing.

This looks like it will be more difficult that I initially thought due to Create hardcoding the boilers engine checks...

Yeah, I had a look at it as well, and it's a bit annoying to set up. It did seem possible, but there is no standard Forge fluid container or anything like that, which is unfortunate.

It doesn't really have anything to do with Forge's fluid system because the boiler doesn't actually store any steam, it just calculates a stress capacity amount based on the amount of heat and water it is receiving, then the engines use that to output their rotational power.