At just nine months old, little Maxwell Drew Johnson appears to already be following in her mother Jessica Simpson's musical footsteps. "Maxwell can whistle on cue at 9 months! Heck, I'm still learning!" joked the pregnant Fashion Star mentor via Twitter Feb. 19. "This lil human impresses me every day."

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Blonde, blue-eyed Maxwell -- whose name pays tribute to Simpson's family and her NFL player fiance's -- will soon have a built-in playmate to bond with when Simpson, 32, and Eric Johnson, 33, welcome their second baby later this year. Confirming their sophomore pregnancy via Twitter on Christmas Day, the couple has already chosen a name for their new arrival, a source tells Us Weekly: Ace.

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The Weight Watchers spokeswoman -- who is not following the diet program during her pregnancy under doctors' orders -- is also busy making other big plans to get ready for baby No. 2. In escrow to purchase The Talk cohost Sharon Osbourne's 11,000-square-foot mansion in Hidden Hills, Calif., Simpson intends to give Osbourne's massive closet a makeover -- into a nursery! "She's already met with designers!" a source tells Us.

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In the meantime, Simpson and Johnson are having fun bonding with only child Maxwell before their hands get even more full. "Motherhood is a dream," Simpson told Katie Couric during a September interview. "It really is absolutely amazing."

This article originally appeared on Jessica Simpson: Daughter Maxwell, 9 Months, "Impresses Me Every Day"