Children's bank interest and the £100 rule

My mum gives my daughter £50 per month, plus top-ups on birthdays. Up until now, she's used a trustee account ("Mrs A Grandparent for Miss B Child"). The balance currently stands at about £8k. As the money is from a grandparent, with a grandparent as trustee, I've been happy that this doesn't get caught by the £100 rule.

We'd like to move the money to an account with a better rate, but my mum is terribly averse to forms, banks and towns in general, and hates setting up new accounts every few years. It would be a lot easier for us if I could set up a trustee account ("Mrs C Parent for Miss B Child"), and my mum would gift into that.

My question is - as the parent, if I am the trustee, will the interest get caught by the £100 rule, even though the money is a gift from a grandparent? I don't think it will, but I would hate to get it wrong.

Thanks for reading