My girls are very similar, sometimes they wont touch their food until the other one shows interest, then they scarf it down. Now I feed separately in their crate, give them 15 minutes and if they havent eaten they wait till next time. I feed twice a day and use a mix of fromm gold adult & fromm grain free, with either some canned tripe or salmon oil. If Im cooking some meat or vegetables I will cut down on the kibble and mix some of that in. But I always use a measuring cup so I dont give too much. As Karlin suggested, I also use tiny bowls so they are pretty much full - it also keeps their ears cleaner if you dont use a snood.
Lady (1 year old tricolour) & Gracie (3 year old blenheim)
"Happiness is a warm puppy" - Charles M. Schulz