I think this is all of them:

HIGH HOPES FOR ADDY by Connie Rose Porter (March 1999)
ADDY?S LITTLE BROTHER by Connie Rose Porter (March 2000)
ADDY?S WEDDING QUILT by Connie Rose Porter (March 2001)
ADDY STUDIES FREEDOM by Connie Rose Porter (March 2002)
ADDY'S SUMMER PLACE by Connie Rose Porter (March 2003)

FELICITY?S NEW SISTER by Valerie Tripp (March 1999)
FELICITY?S DANCING SHOES by Valerie Tripp (March 2000)
FELICITY TAKES A DARE by Valerie Tripp (March 2001)
FELICITY DISCOVERS A SECRET by Valerie Trip, et al (March 2002)

A REWARD FOR JOSEFINA by Valerie Tripp (March 1999)
AGAIN, JOSEFINA! by Valerie Tripp (March 2000)
JOSEFINA?S SONG by Valerie Tripp (March 2001)
JUST JOSEFINA by Valerie Tripp, et al (March 2002)
THANKS TO JOSEFINA by Valerie Tripp (March 2003)

KAYA AND THE RIVER GIRL by Janet Beeler Shaw (March 2003)

KIRSTEN ON THE TRAIL by Janet Beeler Shaw (March 1999)
KIRSTEN AND THE NEW GIRL by Janet Beeler Shaw (March 2000)
KIRSTEN SNOWBOUND! by Janet Beeler Shaw (March 2001)
KIRSTEN AND THE CHIPPEWA by Janet Beeler Shaw (March 2002)
KIRSTEN'S PROMISE by Janet Beeler Shaw (March 2003)

KIT'S HOME RUN by Valerie Tripp (March 2002)
KIT'S TREE HOUSE by Valerie Tripp (March 2003)

MOLLY TAKES FLIGHT by Valerie Tripp (March 1999)
MOLLY AND THE MOVIE STAR by Valerie Tripp (March 2000)
MOLLY MARCHES ON by Valerie Tripp (March 2001)
MOLLYS A+ PARTNER by Valerie Tripp (March 2002)
MOLLY'S PUPPY TALE by Valerie Tripp (March 2003)

SAMANTHA?S WINTER PARTY by Valerie Tripp (May 1999)
SAMANTHA SAVES THE WEDDING by Valerie Tripp (April 2000)
SAMANTHA AND THE MISSING PEARLS by Valerie Tripp (March 2001)
SAMANTHA'S BLUE BICYCLE by Valerie Tripp (March 2002)
SAMANTHA'S SPECIAL TALENT by Sarah Masters Buckey (March 2003)