One thing that Nataliya and I have tried to stress with the kids is how to be polite when they're speaking or asking. We've been pretty successful with David, so nowadays we mostly tweak his grammar. For example:
After swallowing some food, David asks, " Mommy. Give me water, please."
"David," Nataliya replied, "ask 'Mommy, may I have some water, please?'"
David repeats, "Mommy. May I have water, please?"
Smiling, Nataliya answers, "Yes, David."
Julia has been watching this exchange and chimes in. "Mommy. May I have some water, please?"
Nataliya is thrilled that Julia has caught on so quickly. "Yes, Julia!"
Without missing a beat, Julia then responds, "Get it for me now!"
Looks like we have a bit more work to do with Julia...