A plant called "snowflake." It trails and has many sparkling white flowers. Or perhaps a trailing white petunia.

How about a varigated Ivy Geranium? They're so pretty. I've been trying to find one locally, but they only come in arranged baskets. Toni

A trailing blue lobelia would look lovely with the pink geraneum and appreciates a partly shaded location.

I agree with Debbie. I had a pink ivy geranium with a trailing blue lobelia last year, and it the combo was gorgeous together.

Baccopa trails with small white flowers,, vinca vine, Trailing ivies, Lobelia, Sweet Potato vine.
I use Bacopa and Vinca Vine with red Geraniums in my urns.