Can we trigger small eruptions to avoid disastrous ones?

My suggestion:
Move the US congress to Yellowstone and rebuild the capitol building on that site. The constant venting of their condescending bloviations will not only relieve magma pressure, but will also clean all pollution from the Potomac and add 20 feet to the height of the Washington Monument.

That's a creative and interesting idea, and I think in theory it would probably work. But in reality, we don't know enough about the processes involved to act accurately enough to hope to "reduce" the likelihood of problems. We might in fact make things worse.

However in the future, with enough knowledge it might be possible.

Might be technologically possible, but when it comes to assuming liability for damages subsequent to those small eruptions, it all comes to a halt. It's just no good saying you killed hundreds to same hundreds of thousands.

It would be even better if the Government plugged these things with a few million tons of King Edwards, so that if an eruption did happen, then everyone would get a fair share of tasty baked potatoes instead of molten rock.

Far more pleasant.

Glad to see you're still with us. You suddenly disappeared for awhile.

It wouldn't necessarily have to be small eruptions. It could be some sort of geothermal power generation.

Though Rosborne's point about "humanity not knowing enough to really understand what we are doing" is a good one. We might end up with a small eruption without intending it.

youre quite right. Insurance claims will rule after we clean up all the debris and restrt civilization. The USGS has been sorta working on "hydrating the surfaces" for small seismics and aftershocks. Im not sure whether a large volcanic neck can be slightly managed. We don't know how much excess magma energy resides down there in the Snake River hotpot.
California uses the "1000 smokes" area for geothermal but that's a field whose dimensions about which we have fairly good ideas .

"nature Bats Last" is still the way. I and when the Snake River ever takes off, there will be probably nothing we could do about it.
Relieveing seimic stresses on the order of those that we intitiate in fracking or in small fault zones is one thing. "Dousing" a supervolcano caldera is quite another.

Our abilities to predict are getting better so getting out of the way is still the best strategy.
Maybe sometime in the future. Who knows.

do we not need to envelop all these potatoes in aluminium foil?

USGS had drilled sme small test holes near the Vacca caldera in the 50's (when they weren't that smart). One of the things that happened was that the drill holes sealed up with fresh magma as they proceeded.The casings themselves were quickly fluidized and nothing was acquired. I think that the main reason we don't do this today is the costs associated with demonstrating the same thing.
Watering down' seismic areas is lots easier

The "bottle and cap" is completely as they are two solid objects which will not be changing form. The contents are under very little pressure. The volume of the material escaping is enormous and the geologic structure present major problems. A small explosion may be all it takes to accelerate a major disaster.