Don't worry, they are both very young, all children react to silly ,mad behaviour. Grandpa's are supposed to be mad,l bet he wasn't when your own children were young. We were too worried that we'd get it wrong, too bothered about work/ money worries, now you can relax ,enjoy your grandchildren. You don't have to be the wild ,mad one, far too exhausting. When they are a bit older find a niche. What do you do best ? Sing ? Dance ? Read amazing stories? Cook ? I'm the one who makes the best chips/ the best roast potatoes, l make cakes,desserts and serve poppadoms and jelly for breakfast. The way to a man's heart... etc. Good luck find your own talent. They'll love and remember you that way.