Ok, just to clea up any confusion, the following information comes out of my FAA Approved Flight Attendant Manual, verbatim:
"Child restraint devices cannot be used in an aisle seat, in a designated exit row, forward or AFT of an exit row. Should a large non-approved or FAA approved child restraint be brought on board and can not be stowed properly, it must checked. During an emergency, the child must be removed from the restraint and carried to an exit."
"The FAA has approved certain child restraints which may be used by an infant or small child weighing up to 40 pounds during takeoff, landing and Turbulence. All child restraints must have a loabel that states that the restraint confroms to the Highway Traffic Safety Administration Vehicle Standards and it must also bear a label that states the restraint is certified for use about motor vehicles and commerical aircraft. The FAA recommeds the use of of a rear facing child restraint for children weighing under 20 pounds and and a forward facing system for children 20-40 pounds. It is recommended that children weighing more than 40 pounds vuse the standard lap belt (have their own seat). Parents have the option of carrying children under the age of 2 on their laps."
The flight attendant is required the check the car seat to make sure it has the required labels on the seat. If not, you will not be able to use it although the gate agent is required to check as well.
Lap Children:
"Lap children are infants at least 2 days and under 2 years old and are not required to occupy a seat. The accompanying adult will hold the infant in his/her lap; the seat belt must be located around the ADULT ONLY, If there is a seat available next to the adult, then the adult may choose to place the chid in an approved restraint device at not additional charge. Customers may alo purchase a seat to ensure that they are able to use a restraint device. The adult may also choose to place the child in a seperate a/c seat and place the seat belt around the child (THE CHILD MUST BE ABLE TO SIT UPRIGHT AND AND PILLOWS MAY BE USED BEHIND THE CHILD T O ALLOW A BETTER SEATBELT FIT). One lap child per adult is permitted. "
"All children must be secured for taxi, takeoff, landing, turbulence and any time the Fasten Seatbelt sign is on whether they are secured by a child restraint device or secured by a parent holding them" This is major FAA Federal Air Regulation and a FA can be fined for not making sure everyone is secured during these times.
I know this does not really address the nursing issue, but I think the FAA policy is pretty clear on child restraint devices and what consitutes a lap child. Like I said, this information came vebatim out of my flight attendant manual.