No guarantees how similar these are, but sometimes Fantastic Fiction's "Visitors to this page also looked at these authors" can sometimes be of help. For
Dani Pettrey they list...
Irene Hannon
Lynette Eason
Dee Henderson
Colleen Coble
DiAnn Mills
Susan May Warren
Tracie Peterson
Candace Calvert
Lisa Harris
Nancy Mehl
Karen Witemeyer
Patricia Bradley
Terri Blackstock
Tamera Alexander
Kim Vogel Sawyer
Christy Barritt
There are also sites like
http://www.literature-map.com/ &
http://whatshouldireadnext.com/ might be of use.