Little known about Maddie Mod doll history

The brunette on the left is Princess Grace
and the blonde is an actual Maddie Mod.

Maddie Mod was sold
in many different styles of swimsuits.

I have found a lot of information about the Mego Corp., and a lot of photos of Maddie Mod dolls and outfits.  But I've found almost nothing about the history of the doll.
The earliest Maddies have the following written on their backs:
© 1968/PRINCESS GRACE DOLL/HONG KONG.  She's also got HONG KONG written on the nape of her neck.  I'm assuming the dolls were introduced to the public in 1969.
I don't know if Princess Grace was a subsidiary of Mego, or a separate company that Mego bought out about 1970.  I HAVE read that the doll was named after Madeline Abrams, the wife of David Abrams, the founder of Mego.
I don't know when the doll's marking changed, but at some point her back began saying:
©  MEGOCORP. MCMLXX/HONG KONG, and there is nothing on her neck.
My sisters and I received Maddies for Christmas 1970 (and we always liked the clothes for her more than the dolls).
The book Collectible Doll Fashions: 1970s, by Carmen Varrichio, copyright 2003 Schiffer Publishing, shows Maddie outfits sold from 1970 to 1977.  The 1976 and 1977 clothing packaging, although still saying "Maddie Mod" on the front, has a company called Summit Industries Limited as its manufacturer/distributor.  Another piece of trivia: in 1971 Maddie had a boyfriend named Richie with his own line of clothing, although I've never seen either the doll or outfits.
There are some NRFB outfits that I can now find by googling that are dated 1967, I assume for the 1968 market.  Were her outfits sold before she was?
Maddie had her own competitors.  Some of them were: Marcie Mod by A&H Doll Manufacturing Corp., Maxi Mod by Shillman, Mini Mod by Totsy, and Missy Mod by Edico Productions.

I am making an update to this article on Feb. 23, 2021.  Lauren was kind enough to send me to photos of Maddie's boyfriend Richie, and I am adding them here.  Richie's trademark reads © MEGO ®/MCMLXX/MADE IN HONG KONG

Another update, this one from Gina Ford, who sent me two photos of a playset of Maddie, her case and two outfits. (Aug. 15, 2021)

The silver mini dress is called Shimmering Silver.

Note that the case has "Princess Grace" written on it.

Princess Grace, on the right, has an arch to her feet
and she is definitely high-heeled.
Maddie Mod, on the left, has flat feet that are slanted just a little.

MCMLXX translates to 1970.

Maddie Mods are a dime a dozen,
but Richie is very hard to find.