AFAIK, it can't be done on the iPad itself.
. However, I could be wrong - maybe there's an app that'll do this. If so, hopefully someone will be along to tell what they've used.
Marilyn
There is an app called groupspro lite which is free. There is also a paid version (£1.49). The only difference is that the light version only allows 3 mailing lists, the paid version many. Groups can be set on on both versions.
Hope this sorts out your problem.
Sent from my iPad using iPF