AceShowbiz - Alec Baldwin and his wife Hilaria are getting serious about trying for a fifth child, because they are eager to add another girl to the growing family.

Yoga instructor Hilaria gave birth to the newest member of the Baldwin brood in May (17), when little Romeo joined 22-month-old Leonardo, three-year-old Rafael, Carmen, who will turn five next month, and half-sister Ireland, Alec's 22-year-old daughter from his previous marriage to Kim Basinger.

However, both she and The Departed star Alec have been hesitant to rule out the thought of having further children, because young Carmen is desperate for a baby sister - and the new parents are pretty keen on the idea, too.

"This is the problem... I have a daughter, and then I have three boys, and my daughter is very sure that she is going to have a sister," Hilaria told breakfast show Today. "And she does have a sister, she has Ireland, and Ireland is so wonderful and they've got a great relationship, but there's something about a little sister that she really wants."

"I think it's possible...," the busy mum smiled. "Alec thinks it's very possible... He comes from a big family!"

Hilaria admits their home life has been chaos for the past couple of years as they adjusted to their expanding family, but she has since learned how to keep some semblance of order.

"A lot of it is just managing every single moment of the day," she said, revealing she has now mastered their kids' shared bath times: "It's very fast, I'm so efficient."

And even with four children under the age of five, Hilaria and Alec are still able to find quality time for themselves as a couple.

"We spend a lot of time together," she remarked. "Some of my friends are like, 'How many times do you talk during the day?' When the babies are sleeping, we always spend time together and we... just like each other. We're very different, we're extraordinarily different, the complete yin and yang, but we like each other!"

The couple wed in 2012.