removal of conditions for child: 90-day rule confusion

[opsanus 0]

I think I know the answer to this, but of course I am hoping for a more favorable truth. The I-751 instructions do not explicitly clarify the situation of a child who entered the U.S. more than 90 days after his mother (my wife), but then received Permanent Resident status at approximately the same time. In other words: The wording in those instructions does not specifically state anything in reference to the date of K-1 status, and therefore leaves some uncertainty as to the interpretation of our situation. There was a problem with my wife's green card application process, and the result was that although her son arrived more than 7 months later, their applications for green card were processed at about the same time and the cards were received about one month apart, in June and July of 2008. Is it still an absolute that their Removal of Conditions process be in separate applications with separate fees?

[Otto 83]

You may be confusing their date 'entered' with the date their PR/Green Cards expire. The expiration date is what matters. If they're only a month apart (the expiration dates) you may file them both together.