When she left the supermarket she realised she'd forgotten to buy bread and milk, but it was on her way home so she could get them later with the girls. They'd moan of course, they'd probably say
"Oh Mummy, do we have to?"
"Mummy, it's raining and I'm cold, can't we go straight home?"
But she'd say "Sorry, no, we need bread and milk" and that would be that. They'd buy what they needed and go home, perhaps with a little treat for patient girls: chocolate or an ice cream - no, perhaps not ice cream today, too cold.