As a heavy user of "revert to launch" and other savescumming techniques, I rarely have anything go seriously wrong in KSP that I can't undo. Unfortunately, I recently sent out not one but two separate missions using the 3-person capsule topped with Mk25 Parachutes. One to the Mun, one to Minmus. I only realised the problem after I had saved over any possibility to revert, when the Mun lander was attempting to re-enter Kerbin and landed at 80 km/h.
So I reloaded to the last save I did have, which was that lander on its return flight to Kerbin. I used up the last of its fuel circularising the orbit as much as possible, rather than re-entering orbit. "As much as possible" unfortunately was an 80/500 km orbit or thereabouts. Then I sent up a new craft equipped with an engineer, some radial chutes, and a Klaw, and used an engineer in space for a reason other than fulfilling a specific contract for the first time. The rendezvous was a little awkward, but not too much of a problem. Grabbed with Klaw, EVA'd over to install the chutes, and then hopped back in for re-entry. Because it was out of fuel, I used the Klaw to put both craft in the atmosphere before detaching and trying to bring both down separately, but simultaneously.
And that's how I learnt that you can't re-enter two ships at once. I had both under 500 m/s and their chutes armed, when suddenly the one I wasn't looking at at the time disappeared off the map and trying to switch to it with the hotkey didn't work.
So I reloaded again (thankfully just before the Klaw rendezvous) and this time transferred over some fuel (the Klaw said it can't transfer fuel, so I guess that was a lie...one I'll usually pretend is true for verisimilitude, but in this case my verisimilitude can pretend the first attempt with the Klaw dragging to re-entry worked), and re-entered one at a time.
The Minmus ship was still on its way out while all this happened, so I plan to rendezvous with it while landed on Minmus. Figure that's easier than an orbital meeting. The engineer's ship is on its way to Minmus right now.