"Whitney and Bobbi were very close as she was growing up as a teen and becoming a young lady in the last several years when Whitney was alive," Mark Behar says.
He adds: "Whitney was the main one that taught Bobbi how to drive at 15, and was always taking her on shopping dates and having mother-daughter dates throughout the years.
"They used to travel together a lot, and Whitney just adored her. I heard her once say that Bobbi was her 'Mini-Me.' "
Bobbi Kristina died at 22 last weekend, nearly six months after she was found unresponsive in a bathtub in her Roswell, Georgia, home.
The incident echoed her mother's death three years earlier. Houston was found facedown in a bathtub ahead of Clive Davis' annual pre-Grammy party at the Beverly Hilton Hotel in February 2012.
Behar says Houston had big plans for her daughter prior to her passing. "Whitney had Bobbi's whole life planned out in her mind, like where she was going to live, her schooling, her business ideas and ventures, as well as her future when she was not going to be there for her."
Now, Bobbi Kristina and her mother will be reunited when she's laid to rest next to Houston at Fairview Cemetery in Westfield, New Jersey.
Reporting by LINDA MARX