Soubry will probably do it as easily as she managed to convince the people at the second People's Vote march that she's concerned about vulnerable people after Brexit, 3 days after she'd voted to keep the Universal Credit rollout risk assessment private. Or how she's managing to reinvent herself as a champion of the EU, despite voting once out of 15 attempts in favour of EU nationals' right to remain in the UK, to 12 times against and 3 times in favour of the UK's membership of the EU, to 13 times against it. Hell, Soubry took to James O'Brien's show on LBC to say she'd prefer a no-deal Brexit to a Labour government last week and People's Vote haven't disowned her yet. Grieve even managed to survive voting against his own amendment, so I can't see this being a problem for either of them.
Every single person on that list has been vocal in their complaints that Labour prioritise an election over a second referendum. The minute the results of the vote are read and May wins, it'll be a race to see which of them is the first to any TV or radio live microphone within a 50 mile radius to say "Look, we tried to get rid of May and we can't. Time for a second referendum". They know a no confidence vote now will lose, they want it to lose, they just don't want to be the ones who table it. They have absolutely no interest in getting rid of the Tories.