(One thing I think is key to making this kind of informal pareto improvement childcare work is trying really hard as a parent to let the non-parents have the easiest baby-moments, and making it really clear that they're free to give the baby back as soon as they're not enjoying it. Give them a happy giggling baby and take back a sleepy grump who needs a change. You could certainly do some amount of pushing people into looking after your kid when they don't want to out of a duty they feel to help out, but this would not be a good plan. Aside from the damage it does to your relationships to buy childcare with goodwill and social capital, you're also opting for a small amount of free time when it's convenient to you when instead you could have a larger amount of free time total by letting it be when it was convenient for the other person.)