-name or from name. The kid will 100000% not care how it's signed off
If its a kids party i always just put my childs name as its because of my child that im there probably 🤷🏼♀️ so i would just write “love Maisie” as is from a child to a child
Just put 'from' or 'love' <childs name>. The child probably won't even read it so I really wouldn't worry.
Best wishes from?