How about
Sisters by Birth
Friends by choice. is a JD MOC design freebie possibly that stands for Jericho Designs.

or
God made us Sisters
Love made us friends. Have seen it somewhere but can't remember where. sorry.

Hugs n roses, Meganne

I believe there is a nice one on Embroidery Library but don't remember where on the site. It has a heart with ribbon and a saying.

I have used the motherdayblock10 from sick (nobody will really recognise that this are not two sisters walking hand in hand with a balloon ;o) At the moment you can get the complete set for 1,-$.
I had dl a nice pair of girls from ATW (kids-view-brownies) and maybe you can use design atm3443 and leave away the saying "best friends"? I changed the colors cause I don't like brown...
The other two designs with two girls I know: A emily-strawberrydesign at turquoise-blog and a design to stitch a card in RW-view at sewazdesigns.
Hope I could help you :o)
Greetings, Bettina

Beth, you can find the Golden Gals here

Beth, I used this design from Cindes for a sister before with my own text and loved it. Scroll down to 3rd line of designs to a blonde & brunette girl holding a heart.....might work for you, might not... they are all freebies... <br />http://cindysembroiderydesigns.com/Kids_Stuff.html