Junior ISA grandparent payments

[Crunchybiscuit1]

my DC has a Vanguard Junior ISA. Grandparents aren’t allowed to make a regular monthly payment directly into this - instead, they would have to make individual gifts via the website. Can they set up a monthly standing order to my husband and my joint account monthly, and then we pay the money into the Junior ISA? Or are there any tax reasons etc why this wouldn’t be allowed?

This is what we do, although I have to admit I haven't really looked into any potential issues!

Thanks @Yellowtracktor

Tax won’t disallow it, but I have previously wondered if it’s worse from an IHT perspective, for those who are concerned about that. I concluded that I didn’t think it was any worse.
Good to know that Vanguard don’t allow it. We use Fidelity for JISAs, and while I’m not wedded to them, they do allow GPs to set up a direct debit, so maybe I’ll stick with Fidelity for now…