The first year their daughters vacationed in the new house, Diane was 16 and Susan was 12.
"I had a great time playing with other kids on the beach," recalls Susan, now 51.
"I was a bored teenager," says Diane, now 55. Later, though, when she was working, she adds, "I loved getting away to the mountains on weekends."
The Gansslosers raised their daughters in Northeast Philadelphia. Herb was a switch supervisor for Bell Telephone. Martha was a homemaker.
Eventually Diane married Steve Groeber, moved to Cinnaminson, and had a son and daughter. Susan married Larry Fox, remained in Northeast Philadelphia, and also had a son and a daughter.
The four cousins delighted in spending time with their grandparents at Pebble Beach. Herb swam and canoed with the grandchildren. Martha picked wild blueberries with them.
She baked pies, cobblers, and her special blueberry pudding cake for the grandchildren, and kept the pantry - renamed the candy closet - stocked with snacks. In the winter, Herb and his sons-in-law swept snow from the frozen lake so the grandchildren could ice skate.
When Martha was diagnosed with lung cancer, her treatments and Herb's own medical issues meant they spent less time in the mountains. Diane and Susan became caretakers for the vacation home. In 2005, the Gansslosers transferred the title to the house to their daughters.
Before Martha died in 2008, Susan and Diane showed her the "Keep It in the Family, Ganssloser, Groeber, Fox" sign.
"It made her happy," Diane says.
Some neighbors had had to sell their vacation homes because the children refused to take responsibility for them or bickered about upkeep. Diane and Susan say they were determined to make their partnership work.
The house was paid off, and Herb had kept all the receipts for work done. Following his example, Diane began a log for the house. Her father, now 81 and living in a retirement residence in Northeast Philadelphia, is available for advice, she says.
When the kitchen needed updating, the sisters chose colors and materials for the countertop, backsplash, and floor and replaced the avocado-green fridge with almond. They picked out new cocoa carpeting together and agreed to keep the original dark paneling.
"When people say outdated, I say low-maintenance," Diane says.
"It doesn't need to be painted," Susan explains.
The sisters don't always agree on matters of taste. Diane likes the orange kitchen table. Susan thinks it's too bright.
Herb made the table, so it stays. So do the kitchen chairs he acquired from the Bell Telephone cafeteria before he retired in the late 1980s.
Martha crocheted the afghan draped on the sofa. Steve's sister made the quilt above it. Herb's German beer steins are displayed on a corner shelf. The sisters are so in sync that they stitched a floral needlepoint panel together, which hangs up near the beamed ceiling.
Diane, who works part time for a garden center, has more time for chores in the summer than her sister, who manages an orthodontist's office.
Diane power-washed and stained the deck and plants flower beds. "I'll buy a garden ornament and think, 'Mom would like this,' " she says.
Susan stocks the pantry with staples and candy and snacks for the grown-up Ganssloser grandchildren, who still visit often.
Husbands Larry and Steve enjoy fishing and playing tennis and golf, and helping around the mountain house. They installed new windows and sliding doors.
The Gansslosers' grandchildren have told their mothers never to sell the house. But the sisters concede that, when the time comes, it might be difficult to split ownership four ways.
In the meantime, they hope for grandchildren of their own to spend summer with at Pebble Beach.