How to get a Re-entry permit for a 6 months old baby born abroad, parents hold Green Card & Re-Entry-Permits.

google for Beverly Zaslow memo of March 20, 2005 and show this at the Port of Entry to get PR status for baby under 2.
Week of Muster:
Topic:
Headquarters POC:
Office:
Weekly Muster
March 20, 2005
Processing Immigrant Children
Beverly Zaslow (202) 344:1563
Immigration Policy and Programs
Message: This is to remind all officers that, in cases where a child is entering the
United States for the first time with their Lawful Permanent Resident (LPR) or first-time
immigrant parent, a Form 1-1 81, Memorandum of Creation of Record of Lawful I
Permanent Residence, must be completed.
The proper class of admission must be ascribed and a Form 1-1 81 must be completed
for each immigrant child who enters without an immigrant visa. The correct procedure
is stated in Chapter 14.5 of the Inspector's Field Manual (IFM), Admission of Certain
Immigrant Children without Immigrant Visas:
Children may be admitted as new immigrants without presenting an immigrant visa
under two circumstances:
A child born to an accompanying parent after issuance of an immigrant visa to
the parent but prior to the parent's initial admission as an immigrant (XE3, XF3,
XR3 or XN3); or
A child, under 2 years of age, born during a temporary absence of a lawful
permanent resident mother if the child is accompanying the parent who is
reentering the United States as a returning resident for the first time after the
birth of the child (NA3).
You must establish the relationship between parent and child, generally by a birth
certificate (with English translation) and, of course, the admissibility of the parent.
There have been incidents of attempted fraud in such cases, so in doubtful cases,
corroborating evidence such as medical records may be required. Verify the parent's
LPR status using the Central Index System and/or the Image Storage and Retrieval
System.
It is important that you properly record the admission of such new immigrants. If you
are processing a child born subsequent to the issuance of an immigrant visa, use the
following admission symbols: ,

The Beverly Zaslow Memo of March 20, 2005 explains it all, but make sure to have the right documentary proof of the child-parent relationship on you, both when seeking to board the US-bound flight at the point of origin, as well as upon arrival into the US airport.

Your child will automatically become a lawful permanent resident if she is under the age of two and enters the U.S. during your first trip back since her birth. You will be able to file for a re-entry permit for your daughter once she has been granted permanent residence.

There is no reentry permit or visa required for your child if your child accompanies you back upon your first return after your child's birth and your child is under two years old. All you would need is your child's passport and birth certificate.