If the other parent of your child didn't have to WFH during this time, but their work has closed (so they're effectively just at home with nothing to do) yet you had to still WFH 9-5 weekdays, would you expect the other parent to care for your child/ren (for sake of the argument-other parent has no underlying health conditions and none of you are mixing with other people so infection isn't a factor in the scenario) so that you could actually get work done?
AIBU- usual (ie. Currently non-working parent cares for child/ren during weekend only) schedule of care should continue regardless of who needs to work
YANBU- currently non-WFH parent should be caring for the child during the working day
Apologies if this isn't worded very coherently have tried to make this as general as possible