I only have one DD so don't have anything to compare her to. We say ta to her when we give her things and generally say thank you mummy, or thank you daddy afterwards because that is what I'd like her to say when she starts talking properly. I don't take things away if she doesn't say ta though. I think that she's a bit too young for that. She understands what ta means and likes to bring us all kinds of random objects and shove them in our faces whilst saying ta, lol. if I say, "ta to Grandma" she will go and give the object to grandma. Not sure if that helps you but that's our experience