Epoh--how frustrating. Probably this has occurred to you already but it sounds like your FIL is not wanting to do the serious stuff-- just maybe spend more fun time with the kids. There might be room then to hire a nanny for the serious stuff (eg homework, healthy snacks, and taking care of the kids until the end of the work day) and have FIL do something fun for an hour or so a couple of times a week or whatever (or taking them for fun stuff on a weekend for a few hours to give you a rest!). Whatever you decide, good luck!