My youngest won't eat a hamburger but loves meatloaf. I got the idea to add some ground sausage about 6 months ago and it was very well received. My kids are funny too in that my daughter doesn't like ketchup and the boys don't like ketchup based bbq sauce (though they tear trough a bottle of ketchup). They all like marinara though, so my meatloaf gets finished with a little marinara glaze, sprinkle if herbs, and sprinkle of shredded parm the last 5 minutes.