Hi Charlotte,
Thank you for your suggestion - it’s a cracker!
We’re absolutely looking to expand our money management features and enable our users to interrogate their money in more advanced ways - including seeing an aggregated balance across all (or a selection) of your accounts. Hopefully, this will also mean you can view your category spend across certain combinations of accounts as well 
As always, thank you for your support - and please keep the suggestions coming in!
Stay safe,
Tom