I have been using touch ui entirely across all the client from last year or so. I have come across several articles online working with Touch UI and multifields. Multifields always being inconsistent, i always had to devise new strategies to cater to ever changing multifield requirements of clients.
I came across ACS Touch UI multifield and that happen to be very consistent and have started using it across all the clients. ACS uses definition list component where they have shown sample of how they use the multifield. The location of the component is \apps\acs-commons\components\content\definition-list. The component stores the data in the jcr as json. If you can write up a generic iterator which i have you can use this multifield across any component. Happy Component development.