I send my cousins a birthday card and present or money every year and don’t get a thank you message back, they are only kids (pre teen and early teen) but have their own phone and my number so could easily send a quick thank you. They are old enough now to know to say thank you, it’s basic manners and really bugging me and I want to stop doing it. The trouble is I have just had a baby and my Auntie (their mum) will no doubt buy for him but I will always say thank you on his behalf until he’s old enough to say it himself. What do I do?