A quick Google shows:
Robyn married David Preston Jessop in 1999. In 2007, he filed for divorce in Montana, citing “irreconcilable differences.” They were in a monogamous marriage and had three children together: David (who now goes by “Dayton”), Aurora and Breanna. Apparently, David is cousins with Robyn’s sister wife, Christine.
Also, (although I haven't seen them posted), Robyn apparently was assigned certain debts at the dissolution of the marriage, including $1,000 on a Victoria's Secret charge card and "thousands of dollars" owed to Sears and Target. If the kids didn't have cribs, maybe it's because VS doesn't sell cribs. Total debt was something like $32,000.
She probably feels like she hit the jackpot when she married into the Brown bunch.