X17 EXCLUSIVE - Randy Jackson Granted Extension For $600K Child Support Case Against Baby Mama's Wishes

Randy Jackson and the mother of his two children, Alejandra, faced off in an LA courtroom Friday morning over a $600k child support judgement that was awarded to her back in December 1990. The judge ended up siding with Randy.

In court, Alejandra had said her daughter was born in 1999, which would make her 13. However, Jackson's lawyers clarified the age. Since their youngest child, Genevieve, is 22 and an adult ... the judge didn't force Michael's brother to hand over any money, and instead, postponed the case until May 25.

Alejandra claims Randy has not paid his $1,200-a-month child support in years and as a result, the amount now exceeds $600k.

Randy filed a countersuit claiming that Alejandra agreed to a deal back in 1993 that would allow her to live comfortably at the Jackson Encino home instead of receiving payments. This included cooks, maids, food and use of luxury cars. In Randy's suit, it says Alejandra and her kids have lived "like kings and queens at Randy Jackson's expense."

A Jackson insider tells X17online exclusively:

"Randy is a great dad, and his kids are well taken care of. He's excited to get this over with and move on."

Randy never married Alejandra, but they had two children together. Alejandra then went ahead and married his brother Jermaine, against his will and knowledge ... and had two kids with him. Now, after almost two decades, we're told "she's after money from both brothers."