The pair, who welcomed daughter Lucia via surrogate in March — barely six months after Hilaria, 37, gave birth to son Eduardo — have been hunkering down at their Hamptons estate, "where it's a nonstop nightmare," the insider dishes.
"Hilaria's up all night with feedings, and they're both tired and cranky, especially Alec, from taking care of the rest of the kids 24/7."
The couple also shares Romeo Alejandro David, 2, Leonardo Ángel Charles, 4, Rafael Thomas, 5, and daughter Carmen Gabriela, 7. Additionally, Alec also shares 25-year-old daughter Ireland with Kim Basinger.
The actor, 62, who recently returned home full-time, after quarantining while shooting his latest project, "was shocked to find such chaos," the insider spills. "He and Hilaria thought having one more kid would be a cinch, but they're at their wits' end!"
The arrival of baby Lucia — whom the proud mom calls "a dream come true" — was emotional from the get go as Hilaria suffered a miscarriage in 2019. On March 4, she opened up about the significance of the two newest members to the Baldwin family.
"The Baldwinitos craved so much to have a little sister," she began a lengthy Instagram post. "Many of you may remember the loss of their sister at 4 months in the end of 2019. There isn't a day that goes by where we don't ache for our daughter."
In the emotional post, Hilaria shared how she told her daughter and sons that "their sister was going to come, just not at that time."
"Nothing will ever replace her, but two wonderful souls have come into our lives, and we are humbled to know them," she wrote about the two new additions to the family.
"Our children were brave during our time of tremendous grief — braver than us...and they held out hope. To experience and accept life's ups and downs is challenging, but a reality that all of us have no choice but to receive and process," Hilaria continued. "I have learned that often our children are wiser than we are and their wisdom has guided us."
She also said that they refer to "Edu" as the "rainbow baby" and how overwhelmed they feel to have him in this world, adding that they are "living each day," bonding, and are grateful for "all of the very special angels who helped bring Lucía into the world."