I'm not sure about the Mother/Daughter authoring team, but these are the first 4 fics that come to mind for police/FBI related stories:
For Richer or Poorer
» by Mujitsu
COMPLETE!The world of the rich is a glamorous and often deadly place. Detective Kagome Higurashi must infiltrate this world with the help of business tycoon, Sesshoumaru. Let the sparks fly! AU, KagSess Added oneshot up!
Inuyasha - Rated: M - English - Romance/Mystery - Chapters: 18 - Words: 74,782 - Reviews: 576 - Updated: 3-2-06 - Published: 5-4-05 - Sesshomaru & Kagome - Complete
To Bear Witness
by Striking Falcon
A known CEO and his Junior Exec. are being protected by the U. S. Marshals until further notice. What happens when its not someone you're supposed to protect, but something? SK
Inuyasha - Rated: M - English - Humor/Romance - Chapters: 39 - Words: 201,076 - Reviews: 1518 - Updated: 4-22-04 - Published: 7-16-03 - Kagome & Sesshomaru
The Best In The Field
Age is but a number , titles just mere words , but when desire and attraction take over it cannot be ignored nor denied. Inevitably the pull becomes too strong and a twist of cruel fate makes even one such as him take a good hard look at his cold and lonely life.[ COMPLETED ]
Rating: MA ?-? Universe: Alternate ?-? Status: Complete ?-? Category: Chapter Stories ?-? Created: 02 Jul 2009 ?-? Updated: 03 Aug 2009
Genre: Angst, Drama, Erotica, Romance, Tragedy ?-? Chapters: 43 ?-? Reviews: 87 ?-? Words: 143,939 ?-? Reads: 73,860
Unable to Commit
When he is unable to commit to marry, Kagome leaves Inuyasha. Two years later, Sesshoumaru runs into her at the store and is unable to resist. Kagome's job as a police officer has lead her down some interesting paths. Now, it seems someone is out to get her! Who could be going through her loved ones trying to "teach her her place"? (18 is up. Rating is now MA)
Rating: MA - Universe: Alternate - Status: Incomplete - Category: Chapter Stories - Genre: Angst, Dark, Drama, Friendship, Romance, Tragedy - Updated: 05-11-10 - Created: 11-22-09 Chapters: 23 - Reviews: 140 - Words: 57,702 - Reads: 57,797
"This is not the story where Kagome was an FBI agent who lived with a blinded dragon demon and her and Sessy's son, it is different"
This story doesn't ring a bell with me. Out of curiosity, do you happen to remember what this one is called?