How is this done with four? Really?

I can barely do it with two. Notice my technique: both kids in the cart, food spilling out from underneath, bribing both kids with food and drink. I am all about containing the kids in the cart. I can’t have them running around the store. But how will I manage four? They won’t all fit in the cart.
Will I just buy those harnesses and strap two of them to the side of the cart? And get dirty looks and nasty comments for leashing my kids? Then again, you get dirty looks and nasty comments if the kids are running around, too. It seems like a lose-lose situation.
And I refuse to get a sitter or wait until Mark is home and suck up my downtime to do something like GROCERY SHOPPING. No, I must figure this out.
Two carts?
Human chain?
Daycare rope?
HOW??