One of the pitfalls of everyone traveling on the same PNR. My expat British boyfriend can't OLCI when we go from the UK to the US (there's another thread on that topic somewhere in this forum) so if we are on the same PNR, I can't OLCI either. No matter which way you do it, someone's not going to like it. If the system were to change so that you could OLCI with the lap-child/permanent resident alien/whatever, then I'm sure there'd be some who were upset that they got shorted a boarding pass.

That said, there are a couple of threads here about a CP being able to call for a manual upgrade when traveling with a lap child. If your big concern over the OLCI is to get the upgrade, book the child with you then call when your window opens and request the upgrade. If inventory is available, you'll get it. You're going to have to go to the desk to get the child's age verified anyway, so it's not like you're going to make an extra trip just for the bags.