I saw on another thread a poster saying you shouldn't become a step parent without having a discussion about what you'd do if both parents were unable to look after the DC.
It got me thinking because I've never had a discussion with DH about what would happen with DSC if he were to pass away or some other reason he may be unable to care for DSC.
I think anyone who'd just take on DSC too without a thought is a saint tbh but I don't think I could do it personally.