RENEE ZELLWEGER has big plans to welcome a little bundle of joy – and she has good pal Sandra Bullock to thank for helping make her baby dreams come true!

The 44-year-old “Bridget Jones’s Diary” star has enlisted Sandra, 49, to walk her through the complicated process of adop­tion. Sandra’s already done it, in 2010, with her son Louis, now 3.

“Renee has finally reached the point where she’s ready to be a mom, but she realizes her chances of a biological pregnancy have diminished based on her age,” said a source.

“Renee has been focusing on her personal life for the last few years. She finally found a man and now wants nothing more than to start a family.”

The Oscar winner is hot and heavy with Doyle Bramhall II, a rock guitarist she first met in the 1990s when they both were college students at the University of Texas, Austin. They reconnected in 2012, and sparks flew.

“Renee really wants a baby but is concerned about getting pregnant at her age,” said the insider.

Sandy suggested adoption, telling Renee about how much Louis has expanded her heart. And she promised to hold Renee’s hand through the entire process.”

The “Gravity” star has even talked Renee into considering adopting a needy infant from New Orleans, where Louis was born, says the insider.

“Becoming a mom was the best thing that ever happened to Sandy,” the insider added.

“She wants to see Renee experience the same joy.”